Update app.py

app.py

@@ -14,6 +14,8 @@ import os
 import os
 openai.api_key = os.getenv("OPENAI_API_KEY")
  # Replace with your OpenAI API key
+if not openai.api_key:
+    raise EnvironmentError("OPENAI_API_KEY is not set in environment variables.")
 
 # Simple in-session memory
 code_history = []