Better error messages from get_create_event_for_room

changelog.d/11638.misc

@@ -0,0 +1 @@
+Improve the error messages from `get_create_event_for_room`.

synapse/storage/databases/main/state.py

@@ -191,11 +191,15 @@ async def get_create_event_for_room(self, room_id: str) -> EventBase:
  NotFoundError if the room is unknown
  """
  state_ids = await self.get_current_state_ids(room_id)
+
+ if not state_ids:
+ raise NotFoundError(f"Current state for room {room_id} is empty")
+
  create_id = state_ids.get((EventTypes.Create, ""))
 
  # If we can't find the create event, assume we've hit a dead end
  if not create_id:
- raise NotFoundError("Unknown room %s" % (room_id,))
+ raise NotFoundError(f"No create event in current state for room {room_id}")
 
  # Retrieve the room's create event and return
  create_event = await self.get_event(create_id)