fix: Push notifications for invite over federation (#13719)

synapse/handlers/federation_event.py

@@ -2170,6 +2170,7 @@ class FederationEventHandler:
         if instance != self._instance_name:
             # Limit the number of events sent over replication. We choose 200
             # here as that is what we default to in `max_request_body_size(..)`
+            result = {}
             try:
                 for batch in batch_iter(event_and_contexts, 200):
                     result = await self._send_events(