🐛 fix(chat.py): raise HTTPException instead of returning JSONResponse on stream_build error

The function stream_build was returning a JSONResponse with an error message when an exception was raised. This is not the correct way to handle errors in FastAPI. Instead, we should raise an HTTPException with the appropriate status code and error message.

src/backend/langflow/api/v1/chat.py

@@ -105,4 +105,4 @@ async def stream_build(flow_id: str):
         return StreamingResponse(event_stream(flow_id), media_type="text/event-stream")
     except Exception as exc:
         logger.error(exc)
-        return JSONResponse(content={"error": str(exc)})
+        raise HTTPException(status_code=500, detail=str(exc))