Update app.py

app.py

@@ -174,9 +174,9 @@ async def handle_message(message: cl.Message):
             }
         }
 
-        response = await post_tool.arun(
-            post_data,
-            config={"callbacks": [cl.AsyncLangchainCallbackHandler()]}
+        response = await post_tool.ainvoke(
+            json.dumps(post_data),
+            [cl.AsyncLangchainCallbackHandler()]}  # config={"callbacks": 
         )
 
         # --degug!