Enable mypy checking for unreachable code and fix instances. (#8432)

1 files changed, 1 insertions, 1 deletions

diff --git a/synapse/storage/databases/main/stream.py b/synapse/storage/databases/main/stream.py

index 37249f1e3f..1d27439536 100644
--- a/synapse/storage/databases/main/stream.py
+++ b/synapse/storage/databases/main/stream.py
@@ -546,7 +546,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore, metaclass=abc.ABCMeta):
 
     async def get_room_event_before_stream_ordering(
         self, room_id: str, stream_ordering: int
-    ) -> Tuple[int, int, str]:
+    ) -> Optional[Tuple[int, int, str]]:
         """Gets details of the first event in a room at or before a stream ordering
 
         Args: