feat: only stream last chunk if client is connected (#4015)

letta/server/rest_api/streaming_response.py

@@ -332,5 +332,5 @@ class StreamingResponseWithStatusCode(StreamingResponse):
             )
             capture_sentry_exception(exc)
             return
-        if more_body:
+        if more_body and self._client_connected:
             await send({"type": "http.response.body", "body": b"", "more_body": False})