mypy fix

strawberry/subscriptions/protocols/graphql_transport_ws/handlers.py

@@ -89,8 +89,10 @@ async def shutdown(self) -> None:
     def start_timeout(self) -> None:
         #  handle_request should call this once it has sent the
         # websocket.accept() response to start the timeout.
-        timeout_handler = self.handle_connection_init_timeout()
-        self.connection_init_timeout_task = asyncio.create_task(timeout_handler)
+        assert not self.connection_init_timeout_task
+        self.connection_init_timeout_task = asyncio.create_task(
+            self.handle_connection_init_timeout()
+        )
 
     async def handle_connection_init_timeout(self) -> None:
         try:
@@ -157,7 +159,8 @@ async def handle_message(self, message: dict) -> None:
     async def handle_connection_init(self, message: ConnectionInitMessage) -> None:
         if self.connection_timed_out:
             return
-        self.connection_init_timeout_task.cancel()
+        if self.connection_init_timeout_task:
+            self.connection_init_timeout_task.cancel()
 
         if message.payload is not UNSET and not isinstance(message.payload, dict):
             await self.close(code=4400, reason="Invalid connection init payload")