🐛 [#328] Fix no zaken being returned

Author: SilviaAmAm

backend/src/openarchiefbeheer/zaken/api/filtersets.py

@@ -169,7 +169,7 @@ def filter_not_in_destruction_list(
             return queryset
 
         zaken_to_exclude = DestructionListItem.objects.filter(
-            ~Q(status=ListItemStatus.removed)
+            ~Q(status=ListItemStatus.removed), zaak__isnull=False
         ).values_list("zaak__url", flat=True)
 
         return queryset.exclude(url__in=Subquery(zaken_to_exclude))