refactor: Use the PachliError type for ApiError (#739)

In the previous code `PachliError` could correctly chain errors and
generate error messages, `ApiError` didn't, which is why there was the
temporary `ApiError.fmt()` extension function.

Rewrite `ApiError` to implement `PachliError` so it gets these benefits
and to reduce the number of different error-handling mechanisms in the
code.

Main changes:

- `PachliError` is now an interface so it can be extended by other
  error interfaces.
- All the `ApiError` subclasses implement `PachliError`, and can
  specify the error string and interpolated variables at the point of
  declaration.
- Update `ListsRepository` and `ServerRepository` to return
  `PachliError` subclasses.

app/lint-baseline.xml

@@ -124,7 +124,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-ca/strings.xml"
-            line="133"
+            line="132"
             column="5"/>
     </issue>
 
@@ -168,7 +168,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-sl/strings.xml"
-            line="180"
+            line="179"
             column="5"/>
     </issue>
 
@@ -179,7 +179,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-cs/strings.xml"
-            line="194"
+            line="193"
             column="5"/>
     </issue>
 
@@ -190,7 +190,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-bn-rIN/strings.xml"
-            line="201"
+            line="200"
             column="5"/>
     </issue>
 
@@ -212,7 +212,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-sl/strings.xml"
-            line="214"
+            line="213"
             column="5"/>
     </issue>
 
@@ -223,7 +223,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-ca/strings.xml"
-            line="236"
+            line="235"
             column="5"/>
     </issue>
 
@@ -234,7 +234,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-cs/strings.xml"
-            line="237"
+            line="236"
             column="5"/>
     </issue>
 
@@ -245,7 +245,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-bn-rIN/strings.xml"
-            line="242"
+            line="241"
             column="5"/>
     </issue>
 
@@ -267,7 +267,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-hi/strings.xml"
-            line="270"
+            line="269"
             column="5"/>
     </issue>
 
@@ -278,7 +278,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-ca/strings.xml"
-            line="273"
+            line="272"
             column="5"/>
     </issue>
 
@@ -289,21 +289,21 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-ca/strings.xml"
+            line="276"
+            column="5"/>
+    </issue>
+
+    <issue
+        id="MissingQuantity"
+        message="For locale &quot;cs&quot; (Czech) the following quantity should also be defined: `many` (e.g. &quot;10.0 dne&quot;)"
+        errorLine1="    &lt;plurals name=&quot;favs&quot;>"
+        errorLine2="    ^">
+        <location
+            file="src/main/res/values-cs/strings.xml"
             line="277"
             column="5"/>
     </issue>
 
-    <issue
-        id="MissingQuantity"
-        message="For locale &quot;cs&quot; (Czech) the following quantity should also be defined: `many` (e.g. &quot;10.0 dne&quot;)"
-        errorLine1="    &lt;plurals name=&quot;favs&quot;>"
-        errorLine2="    ^">
-        <location
-            file="src/main/res/values-cs/strings.xml"
-            line="278"
-            column="5"/>
-    </issue>
-
     <issue
         id="MissingQuantity"
         message="For locale &quot;cs&quot; (Czech) the following quantity should also be defined: `many` (e.g. &quot;10.0 dne&quot;)"
@@ -311,7 +311,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-cs/strings.xml"
-            line="283"
+            line="282"
             column="5"/>
     </issue>
 
@@ -322,7 +322,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-ca/strings.xml"
-            line="302"
+            line="301"
             column="5"/>
     </issue>
 
@@ -333,7 +333,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-cs/strings.xml"
-            line="313"
+            line="312"
             column="5"/>
     </issue>
 
@@ -344,7 +344,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-cs/strings.xml"
-            line="327"
+            line="326"
             column="5"/>
     </issue>
 
@@ -355,7 +355,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-cs/strings.xml"
-            line="332"
+            line="331"
             column="5"/>
     </issue>
 
@@ -366,7 +366,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-cs/strings.xml"
-            line="337"
+            line="336"
             column="5"/>
     </issue>
 
@@ -377,7 +377,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-bg/strings.xml"
-            line="369"
+            line="368"
             column="5"/>
     </issue>
 
@@ -388,7 +388,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-ca/strings.xml"
-            line="369"
+            line="368"
             column="5"/>
     </issue>
 
@@ -399,7 +399,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-ca/strings.xml"
-            line="397"
+            line="396"
             column="5"/>
     </issue>
 
@@ -410,7 +410,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-ca/strings.xml"
-            line="401"
+            line="400"
             column="5"/>
     </issue>
 
@@ -421,7 +421,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-ca/strings.xml"
-            line="405"
+            line="404"
             column="5"/>
     </issue>
 
@@ -432,7 +432,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-ca/strings.xml"
-            line="409"
+            line="408"
             column="5"/>
     </issue>
 
@@ -443,7 +443,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-cs/strings.xml"
-            line="417"
+            line="416"
             column="5"/>
     </issue>
 
@@ -454,7 +454,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-cs/strings.xml"
-            line="422"
+            line="421"
             column="5"/>
     </issue>
 
@@ -465,7 +465,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-ca/strings.xml"
-            line="425"
+            line="424"
             column="5"/>
     </issue>
 
@@ -476,7 +476,7 @@
         errorLine2="    ^">
         <location
             file="src/main/res/values-cs/strings.xml"
-            line="427"
+            line="426"
             column="5"/>
     </issue>
 
@@ -509,7 +509,7 @@
         errorLine2="                                           ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="34"
+            line="33"
             column="44"/>
     </issue>
 
@@ -520,7 +520,7 @@
         errorLine2="                                                 ^">
         <location
             file="src/main/res/values-tr/strings.xml"
-            line="40"
+            line="39"
             column="50"/>
     </issue>
 
@@ -531,7 +531,7 @@
         errorLine2="                                             ^">
         <location
             file="src/main/res/values-tr/strings.xml"
-            line="40"
+            line="39"
             column="46"/>
     </issue>
 
@@ -542,7 +542,7 @@
         errorLine2="                                     ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="71"
+            line="70"
             column="38"/>
     </issue>
 
@@ -553,7 +553,7 @@
         errorLine2="                                             ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="73"
+            line="72"
             column="46"/>
     </issue>
 
@@ -564,7 +564,7 @@
         errorLine2="                                           ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="79"
+            line="78"
             column="44"/>
     </issue>
 
@@ -575,7 +575,7 @@
         errorLine2="                                            ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="102"
+            line="101"
             column="45"/>
     </issue>
 
@@ -586,7 +586,7 @@
         errorLine2="                                           ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="106"
+            line="105"
             column="44"/>
     </issue>
 
@@ -597,7 +597,7 @@
         errorLine2="                                                ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="107"
+            line="106"
             column="49"/>
     </issue>
 
@@ -608,7 +608,7 @@
         errorLine2="                                     ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="110"
+            line="109"
             column="38"/>
     </issue>
 
@@ -619,7 +619,7 @@
         errorLine2="                                                                     ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="125"
+            line="124"
             column="70"/>
     </issue>
 
@@ -630,7 +630,7 @@
         errorLine2="                                                                             ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="158"
+            line="157"
             column="78"/>
     </issue>
 
@@ -641,7 +641,7 @@
         errorLine2="                                                                ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="164"
+            line="163"
             column="65"/>
     </issue>
 
@@ -652,7 +652,7 @@
         errorLine2="                               ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="200"
+            line="199"
             column="32"/>
     </issue>
 
@@ -663,7 +663,7 @@
         errorLine2="                                          ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="268"
+            line="267"
             column="43"/>
     </issue>
 
@@ -674,7 +674,7 @@
         errorLine2="                                                                                     ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="396"
+            line="395"
             column="86"/>
     </issue>
 
@@ -685,7 +685,7 @@
         errorLine2="                                                                                                                                                                                                                                                                                                     ^">
         <location
             file="src/main/res/values-tr/strings.xml"
-            line="504"
+            line="503"
             column="294"/>
     </issue>
 
@@ -696,7 +696,7 @@
         errorLine2="                                                  ^">
         <location
             file="src/main/res/values-nb-rNO/strings.xml"
-            line="526"
+            line="525"
             column="51"/>
     </issue>
 
@@ -729,7 +729,7 @@
         errorLine2="    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="101"
+            line="100"
             column="5"/>
     </issue>
 
@@ -740,7 +740,7 @@
         errorLine2="    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="288"
+            line="287"
             column="5"/>
     </issue>
 
@@ -751,7 +751,7 @@
         errorLine2="    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="339"
+            line="338"
             column="5"/>
     </issue>
 
@@ -762,7 +762,7 @@
         errorLine2="    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="458"
+            line="457"
             column="5"/>
     </issue>
 
@@ -773,7 +773,7 @@
         errorLine2="    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="633"
+            line="632"
             column="5"/>
     </issue>
 
@@ -1290,7 +1290,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="76"
+            line="75"
             column="13"/>
     </issue>
 
@@ -1301,7 +1301,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="82"
+            line="81"
             column="13"/>
     </issue>
 
@@ -1312,7 +1312,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="103"
+            line="102"
             column="13"/>
     </issue>
 
@@ -1323,7 +1323,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="111"
+            line="110"
             column="13"/>
     </issue>
 
@@ -1334,7 +1334,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="145"
+            line="144"
             column="13"/>
     </issue>
 
@@ -1345,7 +1345,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="204"
+            line="203"
             column="13"/>
     </issue>
 
@@ -1356,7 +1356,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="225"
+            line="224"
             column="13"/>
     </issue>
 
@@ -1367,7 +1367,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="226"
+            line="225"
             column="13"/>
     </issue>
 
@@ -1378,7 +1378,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="249"
+            line="248"
             column="13"/>
     </issue>
 
@@ -1389,7 +1389,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="278"
+            line="277"
             column="13"/>
     </issue>
 
@@ -1400,7 +1400,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="349"
+            line="348"
             column="13"/>
     </issue>
 
@@ -1411,7 +1411,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="389"
+            line="388"
             column="13"/>
     </issue>
 
@@ -1422,7 +1422,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="425"
+            line="424"
             column="13"/>
     </issue>
 
@@ -1433,7 +1433,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="428"
+            line="427"
             column="13"/>
     </issue>
 
@@ -1444,7 +1444,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="429"
+            line="428"
             column="13"/>
     </issue>
 
@@ -1455,7 +1455,7 @@
         errorLine2="            ~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="430"
+            line="429"
             column="13"/>
     </issue>
 
@@ -1466,7 +1466,7 @@
         errorLine2="            ~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="431"
+            line="430"
             column="13"/>
     </issue>
 
@@ -1477,7 +1477,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="432"
+            line="431"
             column="13"/>
     </issue>
 
@@ -1488,7 +1488,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="444"
+            line="443"
             column="13"/>
     </issue>
 
@@ -1499,7 +1499,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="445"
+            line="444"
             column="13"/>
     </issue>
 
@@ -1510,7 +1510,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="496"
+            line="495"
             column="13"/>
     </issue>
 
@@ -1521,7 +1521,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="497"
+            line="496"
             column="13"/>
     </issue>
 
@@ -1532,7 +1532,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="508"
+            line="507"
             column="13"/>
     </issue>
 
@@ -1543,7 +1543,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="509"
+            line="508"
             column="13"/>
     </issue>
 
@@ -1554,7 +1554,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="510"
+            line="509"
             column="13"/>
     </issue>
 
@@ -1565,7 +1565,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="512"
+            line="511"
             column="13"/>
     </issue>
 
@@ -1576,7 +1576,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="550"
+            line="549"
             column="13"/>
     </issue>
 
@@ -1587,7 +1587,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="591"
+            line="590"
             column="13"/>
     </issue>
 
@@ -1598,7 +1598,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="597"
+            line="596"
             column="13"/>
     </issue>
 
@@ -1609,7 +1609,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="625"
+            line="624"
             column="13"/>
     </issue>
 
@@ -1620,7 +1620,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="639"
+            line="638"
             column="13"/>
     </issue>
 
@@ -1631,7 +1631,7 @@
         errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/res/values/strings.xml"
-            line="652"
+            line="651"
             column="13"/>
     </issue>
 

app/src/main/java/app/pachli/TabPreferenceActivity.kt

@@ -65,7 +65,6 @@ import java.util.regex.Pattern
 import javax.inject.Inject
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
-import timber.log.Timber
 
 @AndroidEntryPoint
 class TabPreferenceActivity : BaseActivity(), ItemInteractionListener {
@@ -332,7 +331,6 @@ class TabPreferenceActivity : BaseActivity(), ItemInteractionListener {
                     selectListBinding.progressBar.hide()
                     dialog.dismiss()
                     Snackbar.make(binding.root, R.string.error_list_load, Snackbar.LENGTH_LONG).show()
-                    Timber.w(it.throwable, "failed to load lists")
                 }
             }
         }

app/src/main/java/app/pachli/fragment/SFragment.kt

@@ -129,7 +129,7 @@ abstract class SFragment<T : IStatusViewData> : Fragment(), StatusActionListener
                         val msg = getString(
                             R.string.server_repository_error,
                             accountManager.activeAccount!!.domain,
-                            it.msg(requireContext()),
+                            it.fmt(requireContext()),
                         )
                         Timber.e(msg)
                         try {

core/common/src/main/kotlin/app/pachli/core/common/PachliError.kt

@@ -19,36 +19,41 @@ package app.pachli.core.common
 
 import android.content.Context
 import androidx.annotation.StringRes
+import app.pachli.core.common.string.unicodeWrap
 
 /**
- * Base class for errors throughout the app.
+ * Interface for errors throughout the app.
  *
  * Derive new error class hierarchies for different components using a sealed
  * class hierarchy like so:
  *
  * ```kotlin
  * sealed class Error(
- *     @StringRes resourceId: Int,
+ *     @StringRes override val resourceId: Int,
- *     vararg formatArgs: String,
+ *     override val formatArgs: Array<out String>,
- *     source: PachliError? = null,
+ *     cause: PachliError? = null,
- * ) : PachliError(resourceId, *formatArgs, source = source) {
+ * ) : PachliError {
  *     data object SomeProblem : Error(R.string.error_some_problem)
  *     data class OutOfRange(val input: Int) : Error(
- *         R.string.error_out_of_range
+ *         R.string.error_out_of_range, // "Value %1$d is out of range"
  *         input,
  *     )
- *     data class Fetch(val url: String, val e: PachliError) : Error(
+ *     data class Fetch(val url: String, val cause: PachliError) : Error(
- *         R.string.error_fetch,
+ *         R.string.error_fetch, // "Could not fetch %1$s: %2$s"
  *         url,
- *         source = e,
+ *         cause = cause,
  *     )
  * }
  * ```
  *
- * In this example `SomeProblem` represents an error with no additional context,
+ * In this example `SomeProblem` represents an error with no additional context.
- * `OtherProblem` is an error relating to a URL and the URL will be included in
+ *
- * the error message, and `WrappedError` represents an error that wraps another
+ * `OutOfRange` is an error relating to a single value with no underlying cause.
- * error that was the actual cause.
+ * The value (`input`) will be inserted in the string at `%1$s`.
+ *
+ * `Fetch` is an error relating to a URL with an underlying cause. The URL will be
+ * included in the error message at `%1$s`, and the string representation of the
+ * cause will be included at `%2$s`.
  *
  * Possible string resources for those errors would be:
  *
@@ -57,23 +62,27 @@ import androidx.annotation.StringRes
  * <string name="error_out_of_range">Value %1$d is out of range</string>
  * <string name="error_fetch">Could not fetch %1$s: %2$s</string>
  * ```
- *
- * In that last example the `url` parameter will be interpolated as the first
- * placeholder and the error message from the error passed as the `source`
- * parameter will be interpolated as the second placeholder.
- *
- * @property resourceId String resource ID for the error message
- * @property formatArgs 0 or more arguments to interpolate in to the string resource
- * @property source (optional) The underlying error that caused this error
  */
-open class PachliError(
+interface PachliError {
-    @StringRes private val resourceId: Int,
+    /** String resource ID for the error message. */
-    private vararg val formatArgs: String,
+    @get:StringRes
-    val source: PachliError? = null,
+    val resourceId: Int
-) {
+
-    fun msg(context: Context): String {
+    /** Arguments to be interpolated in to the string from [resourceId]. */
+    val formatArgs: Array<out String>
+
+    /**
+     * The cause of this error. If present the string representation of `cause`
+     * will be set as the last format argument when formatting [resourceId].
+     */
+    val cause: PachliError?
+
+    /**
+     * @return A localised, unicode-wrapped error message for this error.
+     */
+    fun fmt(context: Context): String {
         val args = mutableListOf(*formatArgs)
-        source?.let { args.add(it.msg(context)) }
+        cause?.let { args.add(it.fmt(context)) }
-        return context.getString(resourceId, *args.toTypedArray())
+        return context.getString(resourceId, *args.toTypedArray()).unicodeWrap()
     }
 }

core/data/src/main/kotlin/app/pachli/core/data/repository/ListsRepository.kt

@@ -17,6 +17,7 @@
 
 package app.pachli.core.data.repository
 
+import app.pachli.core.common.PachliError
 import app.pachli.core.network.model.MastoList
 import app.pachli.core.network.model.TimelineAccount
 import app.pachli.core.network.model.UserListRepliesPolicy
@@ -36,26 +37,26 @@ interface HasListId {
 }
 
 /** Errors that can be returned from this repository */
-interface ListsError : ApiError {
+interface ListsError : PachliError {
     @JvmInline
-    value class Create(private val error: ApiError) : ListsError, ApiError by error
+    value class Create(private val error: ApiError) : ListsError, PachliError by error
 
     @JvmInline
-    value class Retrieve(private val error: ApiError) : ListsError, ApiError by error
+    value class Retrieve(private val error: ApiError) : ListsError, PachliError by error
 
     @JvmInline
-    value class Update(private val error: ApiError) : ListsError, ApiError by error
+    value class Update(private val error: ApiError) : ListsError, PachliError by error
 
     @JvmInline
-    value class Delete(private val error: ApiError) : ListsError, ApiError by error
+    value class Delete(private val error: ApiError) : ListsError, PachliError by error
 
-    data class GetListsWithAccount(val accountId: String, private val error: ApiError) : ListsError, ApiError by error
+    data class GetListsWithAccount(val accountId: String, private val error: ApiError) : ListsError, PachliError by error
 
-    data class GetAccounts(override val listId: String, private val error: ApiError) : ListsError, HasListId, ApiError by error
+    data class GetAccounts(override val listId: String, private val error: ApiError) : ListsError, HasListId, PachliError by error
 
-    data class AddAccounts(override val listId: String, private val error: ApiError) : ListsError, HasListId, ApiError by error
+    data class AddAccounts(override val listId: String, private val error: ApiError) : ListsError, HasListId, PachliError by error
 
-    data class DeleteAccounts(override val listId: String, private val error: ApiError) : ListsError, HasListId, ApiError by error
+    data class DeleteAccounts(override val listId: String, private val error: ApiError) : ListsError, HasListId, PachliError by error
 }
 
 interface ListsRepository {

core/data/src/main/kotlin/app/pachli/core/data/repository/ServerRepository.kt

@@ -119,13 +119,14 @@ class ServerRepository @Inject constructor(
     }
 
     sealed class Error(
-        @StringRes resourceId: Int,
+        @StringRes override val resourceId: Int,
-        vararg formatArgs: String,
+        override val formatArgs: Array<out String> = emptyArray<String>(),
-        source: PachliError? = null,
+        override val cause: PachliError? = null,
-    ) : PachliError(resourceId, *formatArgs, source = source) {
+    ) : PachliError {
+
         data class GetWellKnownNodeInfo(val throwable: Throwable) : Error(
             R.string.server_repository_error_get_well_known_node_info,
-            throwable.localizedMessage,
+            throwable.localizedMessage?.let { arrayOf(it) }.orEmpty(),
         )
 
         data object UnsupportedSchema : Error(
@@ -134,24 +135,23 @@ class ServerRepository @Inject constructor(
 
         data class GetNodeInfo(val url: String, val throwable: Throwable) : Error(
             R.string.server_repository_error_get_node_info,
-            url,
+            arrayOf(url, throwable.localizedMessage ?: ""),
-            throwable.localizedMessage,
         )
 
         data class ValidateNodeInfo(val url: String, val error: NodeInfo.Error) : Error(
             R.string.server_repository_error_validate_node_info,
-            url,
+            arrayOf(url),
-            source = error,
+            cause = error,
         )
 
         data class GetInstanceInfoV1(val throwable: Throwable) : Error(
             R.string.server_repository_error_get_instance_info,
-            throwable.localizedMessage,
+            throwable.localizedMessage?.let { arrayOf(it) }.orEmpty(),
         )
 
         data class Capabilities(val error: Server.Error) : Error(
             R.string.server_repository_error_capabilities,
-            source = error,
+            cause = error,
         )
     }
 }

core/network/lint-baseline.xml

@@ -1,4 +1,4 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<issues format="6" by="lint 8.3.0" type="baseline" client="gradle" dependencies="false" name="AGP (8.3.0)" variant="all" version="8.3.0">
+<issues format="6" by="lint 8.3.2" type="baseline" client="gradle" dependencies="false" name="AGP (8.3.2)" variant="all" version="8.3.2">
 
 </issues>

core/network/src/main/kotlin/app/pachli/core/network/Server.kt

@@ -17,7 +17,6 @@
 
 package app.pachli.core.network
 
-import androidx.annotation.StringRes
 import androidx.annotation.VisibleForTesting
 import androidx.annotation.VisibleForTesting.Companion.PRIVATE
 import app.pachli.core.common.PachliError
@@ -296,16 +295,13 @@ data class Server(
     }
 
     /** Errors that can occur when processing server capabilities */
-    sealed class Error(
+    sealed interface Error : PachliError {
-        @StringRes resourceId: Int,
-        vararg formatArgs: String,
-    ) : PachliError(resourceId, *formatArgs) {
         /** Could not parse the server's version string */
-        data class UnparseableVersion(val version: String, val throwable: Throwable) : Error(
+        data class UnparseableVersion(val version: String, val throwable: Throwable) : Error {
-            R.string.server_error_unparseable_version,
+            override val resourceId = R.string.server_error_unparseable_version
-            version,
+            override val formatArgs: Array<String> = arrayOf(version, throwable.localizedMessage ?: "")
-            throwable.localizedMessage,
+            override val cause: PachliError? = null
-        )
+        }
     }
 }
 

core/network/src/main/kotlin/app/pachli/core/network/model/nodeinfo/NodeInfo.kt

@@ -77,10 +77,11 @@ data class NodeInfo(val software: Software) {
     }
 
     sealed class Error(
-        @StringRes resourceId: Int,
+        @StringRes override val resourceId: Int,
-        vararg formatArgs: String,
+    ) : PachliError {
-        source: PachliError? = null,
+        override val formatArgs = emptyArray<String>()
-    ) : PachliError(resourceId, *formatArgs, source = source) {
+        override val cause: PachliError? = null
+
         data object NoSoftwareBlock : Error(R.string.node_info_error_no_software)
         data object NoSoftwareName : Error(R.string.node_info_error_no_software_name)
         data object NoSoftwareVersion : Error(R.string.node_info_error_no_software_version)

core/network/src/main/kotlin/app/pachli/core/network/retrofit/apiresult/ApiResult.kt

@@ -17,6 +17,10 @@
 
 package app.pachli.core.network.retrofit.apiresult
 
+import androidx.annotation.StringRes
+import app.pachli.core.common.PachliError
+import app.pachli.core.network.R
+import app.pachli.core.network.extensions.getServerErrorMessage
 import com.github.michaelbull.result.Err
 import com.github.michaelbull.result.Ok
 import com.github.michaelbull.result.Result
@@ -45,50 +49,57 @@ data class ApiResponse<out T>(
 
 /**
  * A failed response from an API call.
+ *
+ * @param resourceId String resource ID of the error message.
+ * @param throwable The [Throwable] that caused this error. The server
+ * message (if it exists), or [Throwable.getLocalizedMessage] will be
+ * interpolated in to this string at `%1$s`.
  */
-interface ApiError {
+sealed class ApiError(
-    // This has to be Throwable, not Exception, because Retrofit exposes
+    @StringRes override val resourceId: Int,
-    // errors as Throwable
+    val throwable: Throwable,
-    val throwable: Throwable
+) : PachliError {
+    override val formatArgs = (
+        throwable.getServerErrorMessage() ?: throwable.localizedMessage
+        )?.let { arrayOf(it) }.orEmpty()
+    override val cause: PachliError? = null
 
     companion object {
-        fun from(exception: Throwable): ApiError {
+        fun from(throwable: Throwable): ApiError {
-            return when (exception) {
+            return when (throwable) {
-                is HttpException -> when (exception.code()) {
+                is HttpException -> when (throwable.code()) {
-                    in 400..499 -> ClientError.from(exception)
+                    in 400..499 -> ClientError.from(throwable)
-                    in 500..599 -> ServerError.from(exception)
+                    in 500..599 -> ServerError.from(throwable)
-                    else -> Unknown(exception)
+                    else -> Unknown(throwable)
                 }
 
-                is JsonDataException -> JsonParse(exception)
+                is JsonDataException -> JsonParseError(throwable)
-                is IOException -> IO(exception)
+                is IOException -> IoError(throwable)
-                else -> Unknown(exception)
+                else -> Unknown(throwable)
             }
         }
     }
 
-    data class Unknown(override val throwable: Throwable) : ApiError
+    data class Unknown(val exception: Throwable) : ApiError(
+        R.string.error_generic_fmt,
+        exception,
+    )
 }
 
-sealed interface HttpError : ApiError {
+sealed class HttpError(
-    override val throwable: HttpException
+    @StringRes override val resourceId: Int,
-
+    open val exception: HttpException,
-    /**
+) : ApiError(resourceId, exception)
-     * The error message for this error, one of (in preference order):
-     *
-     * - The error body of the response that created this error
-     * - The throwable.message
-     * - Literal string "Unknown"
-     */
-    val message
-        get() = throwable.response()?.errorBody()?.string() ?: throwable.message() ?: "Unknown"
-}
 
 /** 4xx errors */
-sealed interface ClientError : HttpError {
+sealed class ClientError(
+    @StringRes override val resourceId: Int,
+    exception: HttpException,
+) : HttpError(resourceId, exception) {
     companion object {
         fun from(exception: HttpException): ClientError {
             return when (exception.code()) {
+                400 -> BadRequest(exception)
                 401 -> Unauthorized(exception)
                 404 -> NotFound(exception)
                 410 -> Gone(exception)
@@ -97,14 +108,32 @@ sealed interface ClientError : HttpError {
         }
     }
 
-    data class Unauthorized(override val throwable: HttpException) : ClientError
+    /** 400 Bad request */
-    data class NotFound(override val throwable: HttpException) : ClientError
+    data class BadRequest(override val exception: HttpException) :
-    data class Gone(override val throwable: HttpException) : ClientError
+        ClientError(R.string.error_generic_fmt, exception)
-    data class UnknownClientError(override val throwable: HttpException) : ClientError
+
+    /** 401 Unauthorized */
+    data class Unauthorized(override val exception: HttpException) :
+        ClientError(R.string.error_generic_fmt, exception)
+
+    /** 404 Not found */
+    data class NotFound(override val exception: HttpException) :
+        ClientError(R.string.error_404_not_found_fmt, exception)
+
+    /** 410 Gone */
+    data class Gone(override val exception: HttpException) :
+        ClientError(R.string.error_generic_fmt, exception)
+
+    /** All other 4xx client errors */
+    data class UnknownClientError(override val exception: HttpException) :
+        ClientError(R.string.error_generic_fmt, exception)
 }
 
 /** 5xx errors */
-sealed interface ServerError : HttpError {
+sealed class ServerError(
+    @StringRes override val resourceId: Int,
+    exception: HttpException,
+) : HttpError(resourceId, exception) {
     companion object {
         fun from(exception: HttpException): ServerError {
             return when (exception.code()) {
@@ -117,15 +146,32 @@ sealed interface ServerError : HttpError {
         }
     }
 
-    data class Internal(override val throwable: HttpException) : ServerError
+    /** 500 Internal error */
-    data class NotImplemented(override val throwable: HttpException) : ServerError
+    data class Internal(override val exception: HttpException) :
-    data class BadGateway(override val throwable: HttpException) : ServerError
+        ServerError(R.string.error_generic_fmt, exception)
-    data class ServiceUnavailable(override val throwable: HttpException) : ServerError
+
-    data class UnknownServerError(override val throwable: HttpException) : ServerError
+    /** 501 Not implemented */
+    data class NotImplemented(override val exception: HttpException) :
+        ServerError(R.string.error_404_not_found_fmt, exception)
+
+    /** 502 Bad gateway */
+    data class BadGateway(override val exception: HttpException) :
+        ServerError(R.string.error_generic_fmt, exception)
+
+    /** 503 Service unavailable */
+    data class ServiceUnavailable(override val exception: HttpException) :
+        ServerError(R.string.error_generic_fmt, exception)
+
+    /** All other 5xx server errors */
+    data class UnknownServerError(override val exception: HttpException) :
+        ServerError(R.string.error_generic_fmt, exception)
 }
-data class JsonParse(override val throwable: JsonDataException) : ApiError
+
-sealed interface NetworkError : ApiError
+data class JsonParseError(val exception: JsonDataException) :
-data class IO(override val throwable: Exception) : NetworkError
+    ApiError(R.string.error_json_data_fmt, exception)
+
+data class IoError(val exception: IOException) :
+    ApiError(R.string.error_network_fmt, exception)
 
 /**
  * Creates an [ApiResult] from a [Response].

core/network/src/main/res/values-ar/strings.xml

@@ -1,2 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<resources></resources>
+<resources>
+    <string name="error_generic_fmt">وقع خطأ: %s</string>
+    <string name="error_404_not_found_fmt">خادمك لا يدعم هذه الميزة: %1$s</string>
+    <string name="error_network_fmt">وقع خطأ في الشبكة: %s</string>
+</resources>

core/network/src/main/res/values-de/strings.xml

@@ -1,2 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<resources></resources>
+<resources>
+    <string name="error_generic_fmt">Es ist ein Fehler aufgetreten: %s</string>
+    <string name="error_404_not_found_fmt">Dein Server unterstützt diese Funktion nicht: %1$s</string>
+    <string name="error_network_fmt">Ein Netzwerkfehler ist aufgetreten: %s</string>
+</resources>

core/network/src/main/res/values-en-rGB/strings.xml

@@ -1,2 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<resources></resources>
+<resources>
+    <string name="error_generic_fmt">An error occurred: %s</string>
+    <string name="error_404_not_found_fmt">Your server does not support this feature: %1$s</string>
+</resources>

core/network/src/main/res/values-es/strings.xml

@@ -4,4 +4,8 @@
     <string name="node_info_error_no_software_version">versión del programa faltante, vacía o en blanco</string>
     <string name="server_error_unparseable_version">no se pudo analizar \"%1$s\" como una versión: %2$s</string>
     <string name="node_info_error_no_software">no hay bloque sobre el programa</string>
+    <string name="error_generic_fmt">Ha ocurrido un error: %s</string>
+    <string name="error_404_not_found_fmt">Su servidor no soporta esta función: %1$s</string>
+    <string name="error_json_data_fmt">Tu servidor devolvió una respuesta inválida: %1$s</string>
+    <string name="error_network_fmt">Ha ocurrido un error de red: %s</string>
 </resources>

core/network/src/main/res/values-fi/strings.xml

@@ -1,2 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<resources></resources>
+<resources>
+    <string name="error_generic_fmt">Tapahtui virhe: %s</string>
+    <string name="error_404_not_found_fmt">Palvelimesi ei tue tätä ominaisuutta: %1$s</string>
+    <string name="error_network_fmt">Tapahtui verkkovirhe: %s</string>
+</resources>

core/network/src/main/res/values-fr/strings.xml

@@ -1,2 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<resources></resources>
+<resources>
+    <string name="error_generic_fmt">Une erreur s\'est produite : %s</string>
+    <string name="error_404_not_found_fmt">Votre serveur ne prend pas en charge cette fonctionnalité: %1$s</string>
+    <string name="error_network_fmt">Une erreur réseau s\'est produite : %s</string>
+</resources>

core/network/src/main/res/values-in/strings.xml

@@ -1,2 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<resources></resources>
+<resources>
+    <string name="error_generic_fmt">Terjadi error: %s</string>
+    <string name="error_404_not_found_fmt">Server Anda tidak mendukung fitur ini: %1$s</string>
+    <string name="error_network_fmt">Jaringan error: %s</string>
+</resources>

core/network/src/main/res/values-it/strings.xml

@@ -1,2 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<resources></resources>
+<resources>
+    <string name="error_generic_fmt">Si è verificato un errore: %s</string>
+    <string name="error_404_not_found_fmt">Il tuo server non supporta questa feature: %1$s</string>
+    <string name="error_network_fmt">Si è verificato un errore di rete: %s</string>
+</resources>

core/network/src/main/res/values-ja/strings.xml

@@ -1,2 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<resources></resources>
+<resources>
+    <string name="error_generic_fmt">エラーが発生しました: %s</string>
+    <string name="error_404_not_found_fmt">あなたのサーバーはこの機能をサポートしていません: %1$s</string>
+    <string name="error_network_fmt">ネットワーク エラーが発生しました: %s</string>
+</resources>

core/network/src/main/res/values-kab/strings.xml

@@ -1,2 +1,4 @@
 <?xml version="1.0" encoding="utf-8"?>
-<resources></resources>
+<resources>
+    <string name="error_generic_fmt">Tella-d tuccḍa: %s</string>
+</resources>

core/network/src/main/res/values-nl/strings.xml

@@ -4,4 +4,7 @@
     <string name="node_info_error_no_software_name">software naam mist, is leeg of blanco</string>
     <string name="node_info_error_no_software_version">software versie mist, is leeg of blanco</string>
     <string name="server_error_unparseable_version">kon \"%1$s\" niet verwerken als een versie: %2$s</string>
+    <string name="error_generic_fmt">Er deed zich een fout voor: %s</string>
+    <string name="error_404_not_found_fmt">Je server beschikt niet over ondersteuning voor deze feature: %1$s</string>
+    <string name="error_network_fmt">Er deed zich een netwerkfout voor: %s</string>
 </resources>

core/network/src/main/res/values-pt-rBR/strings.xml

@@ -1,2 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<resources></resources>
+<resources>
+    <string name="error_generic_fmt">Ocorreu um erro: %s</string>
+    <string name="error_404_not_found_fmt">Tua instância não suporta este recurso: %1$s</string>
+    <string name="error_network_fmt">Ocorreu um erro de rede: %s</string>
+</resources>

core/network/src/main/res/values-sv/strings.xml

@@ -4,4 +4,7 @@
     <string name="node_info_error_no_software">innehöll inget mjukvarublock</string>
     <string name="node_info_error_no_software_name">mjukvarunamnet saknas, är tomt eller blankt</string>
     <string name="server_error_unparseable_version">Kunde inte analysera \"%1$s\" som en version: %2$s</string>
+    <string name="error_generic_fmt">Ett fel har uppstått: %s</string>
+    <string name="error_404_not_found_fmt">Din server stöder inte denna funktion: %1$s</string>
+    <string name="error_network_fmt">Ett nätverksfel har uppstått: %s</string>
 </resources>

core/network/src/main/res/values/strings.xml

@@ -21,4 +21,8 @@
     <string name="node_info_error_no_software_version">software version is missing, empty, or blank</string>
 
     <string name="server_error_unparseable_version">could not parse \"%1$s\" as a version: %2$s</string>
+    <string name="error_generic_fmt">An error occurred: %s</string>
+    <string name="error_404_not_found_fmt">Your server does not support this feature: %1$s</string>
+    <string name="error_json_data_fmt">Your server returned an invalid response: %1$s</string>
+    <string name="error_network_fmt">A network error occurred: %s</string>
 </resources>

core/network/src/test/kotlin/app/pachli/core/network/retrofit/apiresult/ApiResultCallTest.kt

@@ -89,11 +89,10 @@ class ApiResultCallTest {
                 override fun onResponse(call: Call<ApiResult<String>>, response: Response<ApiResult<String>>) {
                     val error = response.body()?.getError() as? ClientError.NotFound
                     assertThat(error).isInstanceOf(ClientError.NotFound::class.java)
-                    assertThat(error?.message).isEqualTo("not found")
 
-                    val throwable = error?.throwable
+                    val exception = error?.exception
-                    assertThat(throwable).isInstanceOf(HttpException::class.java)
+                    assertThat(exception).isInstanceOf(HttpException::class.java)
-                    assertThat(throwable?.code()).isEqualTo(404)
+                    assertThat(exception?.code()).isEqualTo(404)
                 }
 
                 override fun onFailure(call: Call<ApiResult<String>>, t: Throwable) {
@@ -107,7 +106,7 @@ class ApiResultCallTest {
 
     @Test
     fun `should parse call with IOException as ApiResult-failure`() {
-        val error = Err(IO(IOException()))
+        val error = Err(IoError(IOException()))
 
         networkApiResultCall.enqueue(
             object : Callback<ApiResult<String>> {

core/network/src/test/kotlin/app/pachli/core/network/retrofit/apiresult/ApiTest.kt

@@ -140,8 +140,8 @@ class ApiTest {
 
         val error = responseObject as? ServerError.Internal
         assertThat(error).isInstanceOf(ServerError.Internal::class.java)
-        assertThat(error?.throwable?.code()).isEqualTo(500)
+        assertThat(error?.exception?.code()).isEqualTo(500)
-        assertThat(error?.throwable?.message()).isEqualTo("Server Error")
+        assertThat(error?.exception?.message()).isEqualTo("Server Error")
     }
 
     @Test
@@ -155,8 +155,8 @@ class ApiTest {
 
         val error = responseObject as? ServerError.Internal
         assertThat(error).isInstanceOf(ServerError.Internal::class.java)
-        assertThat(error?.throwable?.code()).isEqualTo(500)
+        assertThat(error?.exception?.code()).isEqualTo(500)
-        assertThat(error?.throwable?.message()).isEqualTo("Server Error")
+        assertThat(error?.exception?.message()).isEqualTo("Server Error")
     }
 
     @Test
@@ -167,9 +167,9 @@ class ApiTest {
                 api.getSiteAsync()
             }
 
-        val error = responseObject.getError() as? IO
+        val error = responseObject.getError() as? IoError
 
-        assertThat(error).isInstanceOf(IO::class.java)
+        assertThat(error).isInstanceOf(IoError::class.java)
     }
 
     @Test
@@ -177,9 +177,9 @@ class ApiTest {
         mockWebServer.enqueue(MockResponse().apply { socketPolicy = SocketPolicy.DISCONNECT_AFTER_REQUEST })
         val responseObject = runBlocking { api.getSiteSync() }
 
-        val error = responseObject.getError() as? IO
+        val error = responseObject.getError() as? IoError
 
-        assertThat(error).isInstanceOf(IO::class.java)
+        assertThat(error).isInstanceOf(IoError::class.java)
     }
 
     @Test
@@ -189,9 +189,9 @@ class ApiTest {
         mockWebServer.enqueue(response)
         val responseObject = api.getSitesAsync().getError()
 
-        val error = responseObject as? JsonParse
+        val error = responseObject as? JsonParseError
 
-        assertThat(error).isInstanceOf(JsonParse::class.java)
+        assertThat(error).isInstanceOf(JsonParseError::class.java)
     }
 
     @Test
@@ -201,11 +201,11 @@ class ApiTest {
 
         val responseObject = api.getSitesAsync().getError()
 
-        val error = responseObject as? IO
+        val error = responseObject as? IoError
 
         // Moshi reports invalid JSON as an IoException wrapping a JsonEncodingException
-        assertThat(error).isInstanceOf(IO::class.java)
+        assertThat(error).isInstanceOf(IoError::class.java)
-        assertThat(error?.throwable).isInstanceOf(JsonEncodingException::class.java)
+        assertThat(error?.exception).isInstanceOf(JsonEncodingException::class.java)
     }
 
     @Test

core/ui/src/main/kotlin/app/pachli/core/ui/BackgroundMessageView.kt

@@ -32,6 +32,7 @@ import android.widget.LinearLayout
 import android.widget.TextView
 import androidx.annotation.DrawableRes
 import androidx.annotation.StringRes
+import app.pachli.core.common.PachliError
 import app.pachli.core.common.extensions.visible
 import app.pachli.core.ui.databinding.ViewBackgroundMessageBinding
 import app.pachli.core.ui.extensions.getDrawableRes
@@ -99,6 +100,10 @@ class BackgroundMessageView @JvmOverloads constructor(
         setup(throwable.getDrawableRes(), throwable.getErrorString(context), listener)
     }
 
+    fun setup(error: PachliError, listener: ((v: View) -> Unit)? = null) {
+        setup(error.getDrawableRes(), error.fmt(context), listener)
+    }
+
     fun setup(message: BackgroundMessage, listener: ((v: View) -> Unit)? = null) {
         setup(message.drawableRes, message.stringRes, listener)
     }

core/ui/src/main/kotlin/app/pachli/core/ui/extensions/PachliErrorExtensions.kt

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2024 Pachli Association
+ *
+ * This file is a part of Pachli.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Pachli is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Pachli; if not,
+ * see <http://www.gnu.org/licenses>.
+ */
+
+package app.pachli.core.ui.extensions
+
+import androidx.annotation.DrawableRes
+import app.pachli.core.common.PachliError
+import app.pachli.core.network.retrofit.apiresult.ClientError
+import app.pachli.core.network.retrofit.apiresult.HttpError
+import app.pachli.core.network.retrofit.apiresult.IoError
+import app.pachli.core.ui.R
+
+/** @return A drawable resource to accompany the error message for this [PachliError]. */
+@DrawableRes
+fun PachliError.getDrawableRes(): Int = when (this) {
+    is IoError -> R.drawable.errorphant_offline
+    is HttpError -> when (this) {
+        is ClientError.NotFound -> R.drawable.elephant_friend_empty
+        else -> R.drawable.errorphant_offline
+    }
+    else -> R.drawable.errorphant_offline
+}

core/ui/src/main/kotlin/app/pachli/core/ui/extensions/ThrowableExtensions.kt

@@ -18,7 +18,9 @@
 package app.pachli.core.ui.extensions
 
 import android.content.Context
+import androidx.annotation.DrawableRes
 import app.pachli.core.common.string.unicodeWrap
+import app.pachli.core.network.R as NR
 import app.pachli.core.network.extensions.getServerErrorMessage
 import app.pachli.core.ui.R
 import com.squareup.moshi.JsonDataException
@@ -26,6 +28,7 @@ import java.io.IOException
 import retrofit2.HttpException
 
 /** @return A drawable resource to accompany the error message for this throwable */
+@DrawableRes
 fun Throwable.getDrawableRes(): Int = when (this) {
     is IOException -> R.drawable.errorphant_offline
     is HttpException -> {
@@ -41,15 +44,15 @@ fun Throwable.getDrawableRes(): Int = when (this) {
 /** @return A unicode-wrapped string error message for this throwable */
 fun Throwable.getErrorString(context: Context): String = (
     getServerErrorMessage() ?: when (this) {
-        is IOException -> String.format(context.getString(R.string.error_network_fmt), localizedMessage)
+        is IOException -> String.format(context.getString(NR.string.error_network_fmt), localizedMessage)
         is HttpException -> {
             if (code() == 404) {
-                String.format(context.getString(R.string.error_404_not_found_fmt), localizedMessage)
+                String.format(context.getString(NR.string.error_404_not_found_fmt), localizedMessage)
             } else {
-                String.format(context.getString(R.string.error_generic_fmt), localizedMessage)
+                String.format(context.getString(NR.string.error_generic_fmt), localizedMessage)
             }
         }
-        is JsonDataException -> String.format(context.getString(R.string.error_json_data_fmt), localizedMessage)
+        is JsonDataException -> String.format(context.getString(NR.string.error_json_data_fmt), localizedMessage)
-        else -> String.format(context.getString(R.string.error_generic_fmt), localizedMessage)
+        else -> String.format(context.getString(NR.string.error_generic_fmt), localizedMessage)
     }
     ).unicodeWrap()

core/ui/src/main/res/values-ar/strings.xml

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">حدث خطأ في الشبكة! يرجى التحقق من اتصالك ثم أعد المحاولة!</string>
-    <string name="error_network_fmt">وقع خطأ في الشبكة: %s</string>
-    <string name="error_generic_fmt">وقع خطأ: %s</string>
-    <string name="error_404_not_found_fmt">خادمك لا يدعم هذه الميزة: %1$s</string>
     <string name="error_generic">وقع هناك خطأ.</string>
     <string name="message_empty">لا شيء هنا.</string>
     <string name="action_retry">أعد المحاولة</string>

core/ui/src/main/res/values-de/strings.xml

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">Ein Netzwerkfehler ist aufgetreten. Bitte überprüfe deine Internetverbindung und versuche es erneut.</string>
-    <string name="error_network_fmt">Ein Netzwerkfehler ist aufgetreten: %s</string>
-    <string name="error_generic_fmt">Es ist ein Fehler aufgetreten: %s</string>
-    <string name="error_404_not_found_fmt">Dein Server unterstützt diese Funktion nicht: %1$s</string>
     <string name="error_generic">Ein Fehler ist aufgetreten.</string>
     <string name="message_empty">Hier ist nichts.</string>
     <string name="action_retry">Erneut versuchen</string>

core/ui/src/main/res/values-en-rGB/strings.xml

@@ -1,7 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">A network error occurred! Please check your connection and try again!</string>
-    <string name="error_generic_fmt">An error occurred: %s</string>
-    <string name="error_404_not_found_fmt">Your server does not support this feature: %1$s</string>
     <string name="error_generic">An error occurred.</string>
 </resources>

core/ui/src/main/res/values-es/strings.xml

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
     <string name="error_network">Ha ocurrido un error de red. Por favor, comprueba tu conexión e inténtalo de nuevo.</string>
-    <string name="error_network_fmt">Ha ocurrido un error de red: %s</string>
-    <string name="error_generic_fmt">Ha ocurrido un error: %s</string>
-    <string name="error_404_not_found_fmt">Su servidor no soporta esta función: %1$s</string>
     <string name="error_generic">Ha ocurrido un error.</string>
     <string name="message_empty">Nada aquí.</string>
     <string name="action_retry">Reintentar</string>
@@ -11,6 +8,5 @@
     <string name="action_view_profile">Perfil</string>
     <string name="action_more">Más</string>
     <string name="action_refresh">Recargar</string>
-    <string name="error_json_data_fmt">Tu servidor devolvió una respuesta inválida: %1$s</string>
     <string name="url_domain_notifier">\u0020(🔗 %s)</string>
 </resources>

core/ui/src/main/res/values-fi/strings.xml

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">Verkkovirhe. Tarkista yhteytesi ja yritä uudelleen.</string>
-    <string name="error_network_fmt">Tapahtui verkkovirhe: %s</string>
-    <string name="error_generic_fmt">Tapahtui virhe: %s</string>
-    <string name="error_404_not_found_fmt">Palvelimesi ei tue tätä ominaisuutta: %1$s</string>
     <string name="error_generic">Tapahtui virhe.</string>
     <string name="message_empty">Täällä ei ole mitään.</string>
     <string name="action_retry">Yritä uudelleen</string>

core/ui/src/main/res/values-fr/strings.xml

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">Une erreur réseau s’est produite ! Veuillez vérifier votre connexion puis réessayez !</string>
-    <string name="error_network_fmt">Une erreur réseau s\'est produite : %s</string>
-    <string name="error_generic_fmt">Une erreur s\'est produite : %s</string>
-    <string name="error_404_not_found_fmt">Votre serveur ne prend pas en charge cette fonctionnalité: %1$s</string>
     <string name="error_generic">Une erreur s’est produite.</string>
     <string name="message_empty">Rien ici.</string>
     <string name="action_retry">Réessayer</string>

core/ui/src/main/res/values-in/strings.xml

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">Terjadi kesalahan pada jaringan! Harap periksa koneksi Anda dan coba lagi!</string>
-    <string name="error_network_fmt">Jaringan error: %s</string>
-    <string name="error_generic_fmt">Terjadi error: %s</string>
-    <string name="error_404_not_found_fmt">Server Anda tidak mendukung fitur ini: %1$s</string>
     <string name="error_generic">Terjadi kesalahan.</string>
     <string name="message_empty">Tidak ada apa pun disini.</string>
     <string name="action_retry">Coba lagi</string>

core/ui/src/main/res/values-it/strings.xml

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">Si è verificato un errore di rete. Per favore controlla la tua connessione e riprova.</string>
-    <string name="error_network_fmt">Si è verificato un errore di rete: %s</string>
-    <string name="error_generic_fmt">Si è verificato un errore: %s</string>
-    <string name="error_404_not_found_fmt">Il tuo server non supporta questa feature: %1$s</string>
     <string name="error_generic">Si è verificato un errore.</string>
     <string name="message_empty">Qui non c\'è nulla.</string>
     <string name="action_retry">Riprova</string>

core/ui/src/main/res/values-ja/strings.xml

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">ネットワークエラーが発生しました。接続を確認してもう一度試してください。</string>
-    <string name="error_network_fmt">ネットワーク エラーが発生しました: %s</string>
-    <string name="error_generic_fmt">エラーが発生しました: %s</string>
-    <string name="error_404_not_found_fmt">あなたのサーバーはこの機能をサポートしていません: %1$s</string>
     <string name="error_generic">エラーが発生しました。</string>
     <string name="message_empty">何もありません。</string>
     <string name="action_retry">再試行</string>

core/ui/src/main/res/values-kab/strings.xml

@@ -5,7 +5,6 @@
     <string name="action_retry">Ɛreḍ tikkelt-nniḍen</string>
     <string name="action_view_profile">Amaɣnu</string>
     <string name="action_more">Ugar</string>
-    <string name="error_generic_fmt">Tella-d tuccḍa: %s</string>
     <string name="action_refresh">Smiren</string>
     <string name="button_done">Immed</string>
 </resources>

core/ui/src/main/res/values-nl/strings.xml

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">Er deed zich een netwerkfout voor. Controleer je verbinding en probeer opnieuw.</string>
-    <string name="error_network_fmt">Er deed zich een netwerkfout voor: %s</string>
-    <string name="error_generic_fmt">Er deed zich een fout voor: %s</string>
-    <string name="error_404_not_found_fmt">Je server beschikt niet over ondersteuning voor deze feature: %1$s</string>
     <string name="error_generic">Er deed zich een fout voor.</string>
     <string name="message_empty">Hier is niets.</string>
     <string name="action_retry">Opnieuw proberen</string>

core/ui/src/main/res/values-pt-rBR/strings.xml

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">Ocorreu um erro de rede. Por favor, verifique tua Internet e tente novamente.</string>
-    <string name="error_network_fmt">Ocorreu um erro de rede: %s</string>
-    <string name="error_generic_fmt">Ocorreu um erro: %s</string>
-    <string name="error_404_not_found_fmt">Tua instância não suporta este recurso: %1$s</string>
     <string name="error_generic">Um erro ocorreu.</string>
     <string name="message_empty">Nada aqui.</string>
     <string name="action_retry">Tentar novamente</string>

core/ui/src/main/res/values-sv/strings.xml

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">Ett nätverksfel uppstod. Kontrollera din anslutning och försök igen.</string>
-    <string name="error_network_fmt">Ett nätverksfel har uppstått: %s</string>
-    <string name="error_generic_fmt">Ett fel har uppstått: %s</string>
-    <string name="error_404_not_found_fmt">Din server stöder inte denna funktion: %1$s</string>
     <string name="error_generic">Ett fel har uppstått.</string>
     <string name="message_empty">Ingenting här.</string>
     <string name="action_retry">Försök igen</string>

core/ui/src/main/res/values/strings.xml

@@ -1,10 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <resources>
     <string name="error_network">A network error occurred. Please check your connection and try again.</string>
-    <string name="error_network_fmt">A network error occurred: %s</string>
-    <string name="error_generic_fmt">An error occurred: %s</string>
-    <string name="error_404_not_found_fmt">Your server does not support this feature: %1$s</string>
-    <string name="error_json_data_fmt">Your server returned an invalid response: %1$s</string>
     <string name="error_generic">An error occurred.</string>
     <string name="message_empty">Nothing here.</string>
     <string name="action_retry">Retry</string>

feature/lists/src/main/kotlin/app/pachli/feature/lists/AccountsInListFragment.kt

@@ -34,6 +34,7 @@ import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.ListAdapter
 import app.pachli.core.activity.emojify
 import app.pachli.core.activity.loadAvatar
+import app.pachli.core.common.PachliError
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
@@ -141,7 +142,7 @@ class AccountsInListFragment : DialogFragment() {
 
                 launch {
                     viewModel.errors.collect {
-                        handleError(it.throwable)
+                        handleError(it)
                     }
                 }
             }
@@ -172,7 +173,7 @@ class AccountsInListFragment : DialogFragment() {
             if (it is Accounts.Loaded) adapter.submitList(it.accounts)
         }.onFailure {
             binding.messageView.show()
-            handleError(it.throwable)
+            handleError(it)
         }
     }
 
@@ -196,11 +197,11 @@ class AccountsInListFragment : DialogFragment() {
             }
         }.onFailure {
             Timber.w(it.throwable, "Error searching for accounts in list")
-            handleError(it.throwable)
+            handleError(it)
         }
     }
 
-    private fun handleError(error: Throwable) {
+    private fun handleError(error: PachliError) {
         binding.messageView.show()
         binding.messageView.setup(error) {
             binding.messageView.hide()

feature/lists/src/main/kotlin/app/pachli/feature/lists/ListsActivity.kt

@@ -43,14 +43,12 @@ import app.pachli.core.activity.extensions.startActivityWithDefaultTransition
 import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
-import app.pachli.core.common.string.unicodeWrap
 import app.pachli.core.data.repository.Lists
+import app.pachli.core.data.repository.ListsError
 import app.pachli.core.data.repository.ListsRepository.Companion.compareByListTitle
 import app.pachli.core.navigation.TimelineActivityIntent
 import app.pachli.core.network.model.MastoList
 import app.pachli.core.network.model.UserListRepliesPolicy
-import app.pachli.core.network.retrofit.apiresult.ApiError
-import app.pachli.core.network.retrofit.apiresult.NetworkError
 import app.pachli.core.ui.BackgroundMessage
 import app.pachli.core.ui.extensions.await
 import app.pachli.feature.lists.databinding.ActivityListsBinding
@@ -113,29 +111,7 @@ class ListsActivity : BaseActivity(), MenuProvider {
 
         lifecycleScope.launch {
             viewModel.errors.collect { error ->
-                when (error) {
+                showMessage(error.fmt(this@ListsActivity))
-                    is Error.Create -> showMessage(
-                        String.format(
-                            getString(R.string.error_create_list_fmt),
-                            error.title.unicodeWrap(),
-                            error.throwable.message.unicodeWrap(),
-                        ),
-                    )
-                    is Error.Delete -> showMessage(
-                        String.format(
-                            getString(R.string.error_delete_list_fmt),
-                            error.title.unicodeWrap(),
-                            error.throwable.message.unicodeWrap(),
-                        ),
-                    )
-                    is Error.Update -> showMessage(
-                        String.format(
-                            getString(R.string.error_rename_list_fmt),
-                            error.title.unicodeWrap(),
-                            error.throwable.message.unicodeWrap(),
-                        ),
-                    )
-                }
             }
         }
 
@@ -220,17 +196,13 @@ class ListsActivity : BaseActivity(), MenuProvider {
         if (result == AlertDialog.BUTTON_POSITIVE) viewModel.deleteList(list.id, list.title)
     }
 
-    private fun bind(state: Result<Lists, ApiError>) {
+    private fun bind(state: Result<Lists, ListsError>) {
         state.onFailure {
             binding.listsRecycler.hide()
             binding.messageView.show()
             binding.swipeRefreshLayout.isRefreshing = false
 
-            if (it is NetworkError) {
+            binding.messageView.setup(it) { viewModel.refresh() }
-                binding.messageView.setup(BackgroundMessage.Network()) { viewModel.refresh() }
-            } else {
-                binding.messageView.setup(BackgroundMessage.GenericError()) { viewModel.refresh() }
-            }
         }
 
         state.onSuccess { lists ->

feature/lists/src/main/kotlin/app/pachli/feature/lists/ListsForAccountFragment.kt

@@ -155,7 +155,7 @@ class ListsForAccountFragment : DialogFragment() {
             binding.listsView.hide()
             binding.messageView.apply {
                 show()
-                setup(it.throwable) {
+                setup(it) {
                     viewModel.refresh()
                     load()
                 }

feature/lists/src/main/kotlin/app/pachli/feature/lists/ListsForAccountViewModel.kt

@@ -24,7 +24,6 @@ import app.pachli.core.data.repository.Lists
 import app.pachli.core.data.repository.ListsError
 import app.pachli.core.data.repository.ListsRepository
 import app.pachli.core.network.model.MastoList
-import app.pachli.core.network.retrofit.apiresult.ApiError
 import com.github.michaelbull.result.Err
 import com.github.michaelbull.result.Ok
 import com.github.michaelbull.result.Result
@@ -67,7 +66,7 @@ class ListsForAccountViewModel @AssistedInject constructor(
     private val _listsWithMembership = MutableStateFlow<Result<ListsWithMembership, FlowError>>(Ok(ListsWithMembership.Loading))
     val listsWithMembership = _listsWithMembership.asStateFlow()
 
-    private val _errors = Channel<Error>()
+    private val _errors = Channel<HasListId>()
     val errors = _errors.receiveAsFlow()
 
     private val listsWithMembershipMap = mutableMapOf<String, ListWithMembership>()
@@ -164,21 +163,21 @@ class ListsForAccountViewModel @AssistedInject constructor(
      *  Marker for errors that can be part of the [Result] in the
      *  [ListsForAccountViewModel.listsWithMembership] flow
      */
-    sealed interface FlowError : ApiError
+    sealed interface FlowError : Error
 
     /** Asynchronous errors from network operations */
     sealed interface Error : ListsError {
         /** Failed to fetch lists, or lists containing a particular account */
         @JvmInline
-        value class GetListsWithAccount(val error: ListsError.GetListsWithAccount) : FlowError, ListsError by error
+        value class GetListsWithAccount(private val error: ListsError.GetListsWithAccount) : FlowError, Error, ListsError by error
 
         @JvmInline
-        value class Retrieve(val error: ListsError.Retrieve) : FlowError, ListsError by error
+        value class Retrieve(private val error: ListsError.Retrieve) : FlowError, Error, ListsError by error
 
         @JvmInline
-        value class AddAccounts(val error: ListsError.AddAccounts) : Error, HasListId by error, ListsError by error
+        value class AddAccounts(private val error: ListsError.AddAccounts) : Error, HasListId by error, ListsError by error
 
         @JvmInline
-        value class DeleteAccounts(val error: ListsError.DeleteAccounts) : Error, HasListId by error, ListsError by error
+        value class DeleteAccounts(private val error: ListsError.DeleteAccounts) : Error, HasListId by error, ListsError by error
     }
 }

feature/lists/src/main/kotlin/app/pachli/feature/lists/ListsViewModel.kt

@@ -17,8 +17,10 @@
 
 package app.pachli.feature.lists
 
+import androidx.annotation.StringRes
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import app.pachli.core.common.string.unicodeWrap
 import app.pachli.core.data.repository.ListsError
 import app.pachli.core.data.repository.ListsRepository
 import app.pachli.core.network.model.UserListRepliesPolicy
@@ -32,14 +34,20 @@ import kotlinx.coroutines.flow.getAndUpdate
 import kotlinx.coroutines.flow.receiveAsFlow
 import kotlinx.coroutines.launch
 
-sealed interface Error : ListsError {
+sealed class Error(
-    val title: String
+    @StringRes override val resourceId: Int,
+    override val formatArgs: Array<out String>,
+    override val cause: ListsError? = null,
+) : ListsError {
 
-    data class Create(override val title: String, private val error: ListsError.Create) : Error, ListsError by error
+    data class Create(val title: String, override val cause: ListsError.Create) :
+        Error(R.string.error_create_list_fmt, arrayOf(title.unicodeWrap()), cause)
 
-    data class Delete(override val title: String, private val error: ListsError.Delete) : Error, ListsError by error
+    data class Delete(val title: String, override val cause: ListsError.Delete) :
+        Error(R.string.error_delete_list_fmt, arrayOf(title.unicodeWrap()), cause)
 
-    data class Update(override val title: String, private val error: ListsError.Update) : Error, ListsError by error
+    data class Update(val title: String, override val cause: ListsError.Update) :
+        Error(R.string.error_rename_list_fmt, arrayOf(title.unicodeWrap()), cause)
 }
 
 @HiltViewModel