API: Fix deleting checkin-lists (Z#23170525) (PRETIXEU-AS5) (#4600)

doc/api/resources/checkinlists.rst

@@ -342,7 +342,7 @@ Endpoints
 
 .. http:delete:: /api/v1/organizers/(organizer)/events/(event)/checkinlist/(id)/
 
-   Delete a check-in list. Note that this also deletes the information on all check-ins performed via this list.
+   Delete a check-in list. **Note that this also deletes the information on all check-ins performed via this list.**
 
    **Example request**:
 

src/pretix/api/views/checkin.py

@@ -143,7 +143,9 @@ class CheckinListViewSet(viewsets.ModelViewSet):
             data=self.request.data
         )
 
+    @transaction.atomic
     def perform_destroy(self, instance):
+        instance.checkins.all().delete()
         instance.log_action(
             'pretix.event.checkinlist.deleted',
             user=self.request.user,