Added no junk folder error message

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -6394,7 +6394,7 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
 
                     EntityFolder junk = db.folder().getFolderByType(message.account, EntityFolder.JUNK);
                     if (junk == null)
-                        return null;
+                        throw new IllegalArgumentException(context.getString(R.string.title_no_junk_folder));
 
                     EntityOperation.queue(context, message, EntityOperation.MOVE, junk.id);
 
@@ -6404,7 +6404,6 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
                             rule.id = db.rule().insertRule(rule);
                     }
 
-
                     db.setTransactionSuccessful();
                 } finally {
                     db.endTransaction();
@@ -6417,7 +6416,17 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
 
             @Override
             protected void onException(Bundle args, Throwable ex) {
-                Log.unexpectedError(getParentFragmentManager(), ex);
+                if (ex instanceof IllegalArgumentException) {
+                    Snackbar snackbar = Snackbar.make(view, ex.getMessage(), Snackbar.LENGTH_INDEFINITE);
+                    snackbar.setAction(R.string.title_fix, new View.OnClickListener() {
+                        @Override
+                        public void onClick(View view) {
+                            startActivity(new Intent(getContext(), ActivitySetup.class));
+                        }
+                    });
+                    snackbar.show();
+                } else
+                    Log.unexpectedError(getParentFragmentManager(), ex);
             }
         }.execute(this, args, "message:junk");
     }

app/src/main/res/values/strings.xml

@@ -639,6 +639,7 @@
     <string name="title_no_password">Password missing</string>
     <string name="title_no_inbox">Inbox not found</string>
     <string name="title_no_primary_drafts">No primary account or no drafts folder</string>
+    <string name="title_no_junk_folder">There is no spam folder selected for this account</string>
     <string name="title_no_identities">Sending emails requires at least one identity and a drafts folder</string>
     <string name="title_no_standard">This provider uses a proprietary email protocol and therefore it is not possible to use third party email clients</string>
     <string name="title_no_idle">This provider does not support push messages. This will delay reception of new messages and increase battery usage.</string>