Update app.py

app.py

@@ -50,8 +50,8 @@ async def on_message(message: cl.Message):
 
     llm_chain = cl.user_session.get("runnable")
 
-    response = await llm_chain.ainvoke(
-        {"input": message.content}, callbacks = [cl.AsyncLangchainCallbackHandler()]
+    response = llm_chain.invoke(
+        {"input": message.content}, callbacks = [cl.LangchainCallbackHandler()]
     )
 
     await cl.Message(response["output"].replace("`", "")).send()