Update app.py

app.py

@@ -4,7 +4,7 @@ from typing import Optional
 import openai
 import streamlit as st
 from langchain_core.messages import AIMessage, HumanMessage
-from openai import OpenAI
+from openai import OpenAI, OpenAIError
 
 from rag.runnable_and_memory import get_runnable_and_memory
 from utils.error_message_template import ERROR_MESSAGE