Return correct Http Statuscode on broken iCal feed

aleksis/core/views.py

@@ -1577,7 +1577,7 @@ class ICalFeedView(DetailView):
             kwargs["person"] = obj.person
             return obj.ical_feed_object()(request, *args, **kwargs)
         else:
-            return HttpResponse(status=204)
+            return HttpResponse(status=410)
 
 
 class ICalFeedListView(PermissionRequiredMixin, ListView):