Update app.py

app.py

@@ -25,7 +25,7 @@ def chat(message, history):
 
     try:
         response = query_engine.query(message)
-        return response
+        return str(response)
     except Exception as e:
         print(f"Error generating response: {e}")
         return "I'm still learning how to answer that question. Please try asking something else."