Fix a crash which can happen when user signs out.

The crypto DB has been deleted, and the key download request is cancelled, but in the catch block we tried to write to the deleted DB

changelog.d/3720.bugfix

@@ -0,0 +1 @@
+Fix a crash which can happen when user signs out

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/DeviceListManager.kt

@@ -16,6 +16,7 @@
 
 package org.matrix.android.sdk.internal.crypto
 
+import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.launch
 import org.matrix.android.sdk.api.MatrixPatterns
 import org.matrix.android.sdk.api.auth.data.Credentials
@@ -336,7 +337,12 @@ internal class DeviceListManager @Inject constructor(private val cryptoStore: IM
             downloadKeysForUsersTask.execute(params)
         } catch (throwable: Throwable) {
             Timber.e(throwable, "## CRYPTO | doKeyDownloadForUsers(): error")
-            onKeysDownloadFailed(filteredUsers)
+            if (throwable is CancellationException) {
+                // the crypto module is getting closed, so we cannot access the DB anymore
+                Timber.w("The crypto module is closed, ignoring this error")
+            } else {
+                onKeysDownloadFailed(filteredUsers)
+            }
             throw throwable
         }
         Timber.v("## CRYPTO | doKeyDownloadForUsers() : Got keys for " + filteredUsers.size + " users")