Result may be None

synapse/handlers/room_list.py

@@ -329,7 +329,7 @@ class RoomListHandler(BaseHandler):
         result = yield self.generate_room_entry(room_id, num_joined_users)
 
         if from_federation and not self.config.allow_non_federated_in_public_rooms:
-            if result["m.federate"] is False:
+            if not result or result["m.federate"] is False:
                 # This is a non-federating room and the config has chosen not
                 # to show these rooms to other servers
                 return