Minor Changes #11400 `0e7c765` Thanks @thushanth-bengre-langchain! - fix(google-genai): throw a typed, catchable `EmptyContentError` instead of silently returning empty content / an empty `generations` array when a non-streaming call (`.invoke()`, `.generate()`, `.batch()`) gets back a Gemini candidate with no content — whether from an explicit block (safety/recitation filter, rejected prompt) or the model just not producing usable output (a malformed function call, a thinking model exhausting its token budget). The streaming path (`.stream()`) is unaffected by this behavior change; it now safely skips a contentless chunk instead of throwing a raw `TypeError`.

Patch Changes #11405 `8cfff4d` Thanks @hntrl! - Add LangSmith gateway support for Google Gemini (Developer API) models. When `LANGSMITH_GATEWAY` is set, `ChatGoogleGenerativeAI` and `ChatGoogle` (and `initChatModel("google-genai:...")`) route requests through the gateway's Gemini path, using the gateway key (falling back to `LANGSMITH_API_KEY`). An explicit `baseUrl`/`endpoint`, an explicit `apiKey`, or a Vertex AI configuration suppress gateway routing. Also adds `GEMINI_API_KEY` as a fallback env var for…