Update app.py

app.py

@@ -17,6 +17,9 @@ def codeinterpreter(openai_key,prompt, files):
         for idx, file in enumerate(files):
             fileList.append(file)
 
+    if openai_api_key == "":
+        return ['openai key must set!'，None]
+
     with CodeInterpreterSession(model="gpt-3.5-turbo",openai_api_key=openai_key) as session:
     #async with CodeInterpreterSession(model="gpt-3.5-turbo",openai_api_key="") as session:
         response = session.generate_response_sync(prompt, fileList,True)