Update app.py

app.py

@@ -41,6 +41,11 @@ YOUTUBE_URL_3 = "https://www.youtube.com/watch?v=vw-KWfKwvTQ"
 MODEL_NAME  = "gpt-4"
 
 def invoke(openai_api_key, use_rag, prompt):
+    if (openai_api_key == ""):
+        print(use_rag)
+        raise gr.Error("'OpenAI API Key' is required.")
+    if (prompt == ""):
+        raise gr.Error("'Prompt' is required.")
     try:
         llm = ChatOpenAI(model_name = MODEL_NAME, 
                          openai_api_key = openai_api_key,