Update app.py

app.py

@@ -90,17 +90,24 @@ async def on_chat_start():
 
 @cl.on_message
 async def on_message(message: cl.Message):
-    runnable = cl.user_session.get("runnable")  # type: Runnable
-
-    msg = cl.Message(content="")
-
-    async for chunk in runnable.astream(
-        {"question": message.content},
-        config=RunnableConfig(callbacks=[cl.LangchainCallbackHandler()]),
-    ):
-        await msg.stream_token(chunk)
-
-    await cl.Message(content=response).send()
+    try:
+        logger.info('Starting application')
+        # Your main application logic here
+        runnable = cl.user_session.get("runnable")  # type: Runnable
+    
+        msg = cl.Message(content="")
+    
+        async for chunk in runnable.astream(
+            {"question": message.content},
+            config=RunnableConfig(callbacks=[cl.LangchainCallbackHandler()]),
+        ):
+            await msg.stream_token(chunk)
+    
+        await cl.Message(content=response).send()
+            logger.info('Application finished successfully')
+    except Exception as e:
+        logger.exception("Unhandled exception: %s", e)
+        
 
 # @cl.on_message
 # async def main(question):