Fix event filter

AKModel/views/ak.py

@@ -114,7 +114,7 @@ class AKJSONExportView(AdminViewMixin, FilterByEventSlugMixin, ListView):
             if (values := AKSlot.objects.select_related().filter(ak__pk=ak_id, fixed=True)).exists()
         }
 
-        if DefaultSlot.objects.filter(event=self).exists():
+        if DefaultSlot.objects.filter(event=self.event).exists():
             # discretize default slots if they exists
             blocks = merge_blocks(self.event.default_time_slots(slots_in_an_hour=SLOTS_IN_AN_HOUR))
         else: