Fix: Add assertions to ensure demo is always valid for Spaces

app.py

@@ -1014,19 +1014,25 @@ except Exception as e:
     logger.info(f"Error demo created: {type(demo)}")
 
 # Final verification - ensure demo exists and is valid
+# This is CRITICAL for Spaces - the demo variable MUST exist and be a valid Gradio object
 if demo is None:
-    logger.error("CRITICAL: Demo variable is None!")
-    with gr.Blocks() as demo:
+    logger.error("CRITICAL: Demo variable is None! Creating fallback demo.")
+    with gr.Blocks(title="CGT-LLM-Beta RAG Chatbot") as demo:
         gr.Markdown("# Error: Demo was not created properly\n\nPlease check the logs for details.")
 elif not isinstance(demo, (gr.Blocks, gr.Interface)):
     logger.error(f"CRITICAL: Demo is not a valid Gradio object: {type(demo)}")
-    with gr.Blocks() as demo:
+    with gr.Blocks(title="CGT-LLM-Beta RAG Chatbot") as demo:
         gr.Markdown(f"# Error: Invalid demo type\n\nDemo type: {type(demo)}\n\nPlease check the logs for details.")
 else:
     logger.info(f"✅ Final demo check passed: demo type={type(demo)}")
     # Explicit print to ensure demo is accessible (Spaces might check this)
     print(f"DEMO_VARIABLE_SET: {type(demo)}")
 
+# CRITICAL: Ensure demo is always set for Spaces
+# Spaces will look for a variable named 'demo' at module level
+assert demo is not None, "Demo must be set for Spaces"
+assert isinstance(demo, (gr.Blocks, gr.Interface)), f"Demo must be a Gradio object, got {type(demo)}"
+
 # For local execution only (not on Spaces)
 if __name__ == "__main__":
     if not IS_SPACES: