Added placeholder error timetable entry when parsing errors occur

lib/view/pages/timetable/timetable.dart

@@ -200,14 +200,14 @@ class _TimetableState extends State<Timetable> {
           notes: element.activityType,
           color: _getEventColor(element.code, startTime, endTime),
         );
-      } on Error catch(e) {
-        log(e.toString());
+      } catch(e) {
         return Appointment(
+          id: element,
           startTime: _parseWebuntisTimestamp(element.date, element.startTime),
           endTime: _parseWebuntisTimestamp(element.date, element.endTime),
-          subject: "ERROR",
+          subject: "Fehler",
           notes: element.info,
-          location: 'LOCATION',
+          location: 'Lesefehler',
           color: Theme.of(context).primaryColor,
           startTimeZone: '',
           endTimeZone: '',