Validate OpenAI key before executing anything

app.py

@@ -1,13 +1,22 @@
+import os
+
 import gradio as gr
+import requests
 from langchain.chains import RetrievalQA
-from langchain.llms import OpenAI
 from langchain.document_loaders import PDFMinerLoader
 from langchain.indexes import VectorstoreIndexCreator
-import os
+from langchain.llms import OpenAI
 
 
 def set_openai_key(raw_key):
+    # Check if the API is valid
+    headers = {"Authorization": f"Bearer {raw_key}"}
+    response = requests.get("https://api.openai.com/v1/engines", headers=headers)
+    if response.status_code != 200:
+        raise gr.Error("API key is not valid. Check the key and try again.")
+    
     os.environ["OPENAI_API_KEY"] = raw_key
+    
     return gr.File.update(interactive=True)