4 files changed, 9 insertions, 3 deletions

diff --git a/src/mailman/rest/helpers.py b/src/mailman/rest/helpers.py
index 0cdd40e7e..e20324cfd 100644
--- a/src/mailman/rest/helpers.py
+++ b/src/mailman/rest/helpers.py
@@ -134,7 +134,9 @@ class CollectionMixin:
 
     def _resource_as_json(self, resource):
         """Return the JSON formatted representation of the resource."""
-        return etag(self._resource_as_dict(resource))
+        resource = self._resource_as_dict(resource)
+        assert resource is not None, resource
+        return etag(resource)
 
     def _get_collection(self, request):
         """Return the collection as a concrete list.
@@ -175,6 +177,7 @@ class CollectionMixin:
         if len(collection) != 0:
             entries = [self._resource_as_dict(resource)
                        for resource in collection]
+            assert None not in entries, entries
             # Tag the resources but use the dictionaries.
             [etag(resource) for resource in entries]
             # Create the collection resource
diff --git a/src/mailman/rest/post_moderation.py b/src/mailman/rest/post_moderation.py
index 207294e7d..f641ba9d2 100644
--- a/src/mailman/rest/post_moderation.py
+++ b/src/mailman/rest/post_moderation.py
@@ -142,7 +142,9 @@ class HeldMessages(_HeldMessageBase, CollectionMixin):
 
     def _resource_as_dict(self, request):
         """See `CollectionMixin`."""
-        return self._make_resource(request.id)
+        resource = self._make_resource(request.id)
+        assert resource is not None, resource
+        return resource
 
     def _get_collection(self, request):
         requests = IListRequests(self._mlist)
diff --git a/src/mailman/rest/sub_moderation.py b/src/mailman/rest/sub_moderation.py
index ebb09b9b3..5d6ebce7b 100644
--- a/src/mailman/rest/sub_moderation.py
+++ b/src/mailman/rest/sub_moderation.py
@@ -65,6 +65,7 @@ class IndividualRequest(_ModerationBase):
         # the pending table.
         try:
             resource = self._resource_as_dict(self._token)
+            assert resource is not None, resource
         except LookupError:
             not_found(response)
             return
diff --git a/src/mailman/rest/tests/test_moderation.py b/src/mailman/rest/tests/test_moderation.py
index e1d1f9ab3..63284c808 100644
--- a/src/mailman/rest/tests/test_moderation.py
+++ b/src/mailman/rest/tests/test_moderation.py
@@ -69,7 +69,7 @@ Something else.
         self.assertEqual(cm.exception.code, 400)
 
     def test_missing_held_message_request_id(self):
-        # Bad request when the request_id is not in the database.
+        # Not found when the request_id is not in the database.
         with self.assertRaises(HTTPError) as cm:
             call_api('http://localhost:9001/3.0/lists/ant@example.com/held/99')
         self.assertEqual(cm.exception.code, 404)