loadable error screen, reload actions, autoreload

lib/state/app/modules/marianumMessage/dataProvider/marianum_message_get_messages.dart

@@ -6,6 +6,7 @@ class MarianumMessageGetMessages extends DataLoader<MarianumMessageList> {
   @override
   Future<MarianumMessageList> fetch() async {
     await Future.delayed(const Duration(seconds: 3));
+    throw UnimplementedError("Test");
     return const MarianumMessageList(base: '', messages: [MarianumMessage(date: '', name: 'RepoTest', url: '')]);
   }
 }