Fix syntax JSON parse query

app.py

@@ -275,7 +275,8 @@ chatbot = RAGMedicalChatbot(model_name="gemini-2.5-flash-preview-04-17", retriev
 async def chat_endpoint(req: Request):
     body = await req.json()
     user_id = body.get("user_id", "anonymous")
-    query   = body.get("query", "").strip()
+    query_raw = body.get("query")
+    query = query_raw.strip() if isinstance(query_raw, str) else ""
     lang    = body.get("lang", "EN")
     image_base64 = body.get("image_base64", None)
     # LLM Only