Fix potential crashes due to cash clean

app/build.gradle

@@ -6,8 +6,8 @@ android {
     defaultConfig {
         minSdkVersion 16
         targetSdkVersion 28
-        versionCode 269
-        versionName "2.0.1"
+        versionCode 270
+        versionName "2.0.2"
         multiDexEnabled true
         renderscriptTargetApi 28 as int
         renderscriptSupportModeEnabled true

app/src/main/java/app/fedilab/android/client/API.java

@@ -990,6 +990,8 @@ public class API {
 
         SQLiteDatabase db = Sqlite.getInstance(context, Sqlite.DB_NAME, null, Sqlite.DB_VERSION).open();
         statuses  = new TimelineCacheDAO(context, db).get(max_id);
+
+        if( statuses != null){
             Iterator<Status> i = statuses.iterator();
             List<String> ids = new ArrayList<>();
             while (i.hasNext()) {
@@ -1001,6 +1003,8 @@ public class API {
                     ids.add(s.getId());
                 }
             }
+        }
+
         if( statuses == null){
             return getHomeTimeline(max_id);
         }else{