fix: return the exception's string representation

program/views.py

@@ -614,11 +614,8 @@ class APIScheduleViewSet(
             resolution = resolve_conflicts(request.data, pk, show_pk)
         # FIXME: Find a better way to do this.
         # The exception is thrown by the instantiate_upcoming_schedule function.
-        except RRule.DoesNotExist:
-            return JsonResponse(
-                {"rruleId": ["Ungültige rrule - Object existiert nicht."]},
-                status=status.HTTP_400_BAD_REQUEST,
-            )
+        except RRule.DoesNotExist as exc:
+            return JsonResponse({"rruleId": str(exc)}, status=status.HTTP_400_BAD_REQUEST)
         except ScheduleConflictError as exc:
             return Response(exc.conflicts, status.HTTP_409_CONFLICT)