Add explicit demo validation and error handling for Spaces

app.py

@@ -880,14 +880,24 @@ def create_demo_for_spaces():
 # Check if we're on Spaces
 IS_SPACES = os.getenv("SPACE_ID") is not None or os.getenv("SYSTEM") == "spaces"
 
-# Create demo - Spaces will use it, local execution will override in main()
-if IS_SPACES:
-    logger.info("Initializing for Hugging Face Spaces...")
-    demo = create_demo_for_spaces()
-    logger.info(f"Demo created: {type(demo)}")
-else:
-    # Local execution: demo will be created in main()
-    demo = None
+# Create demo unconditionally at module level - Spaces needs this
+# For local execution, main() will create its own demo
+try:
+    if IS_SPACES:
+        logger.info("Initializing for Hugging Face Spaces...")
+    demo = create_demo_for_spaces() if IS_SPACES else None
+    if IS_SPACES and demo is not None:
+        logger.info(f"Demo created successfully: {type(demo)}")
+        # Verify demo is a valid Gradio object
+        if not isinstance(demo, (gr.Blocks, gr.Interface)):
+            logger.error(f"Demo is not a valid Gradio object: {type(demo)}")
+            raise TypeError(f"Expected gr.Blocks or gr.Interface, got {type(demo)}")
+except Exception as e:
+    logger.error(f"Failed to create demo for Spaces: {e}", exc_info=True)
+    # Create a fallback error demo so Spaces doesn't show blank
+    with gr.Blocks() as error_demo:
+        gr.Markdown(f"# Error Initializing Chatbot\n\nAn error occurred while initializing the chatbot.\n\nError: {str(e)}\n\nPlease check the logs for details.")
+    demo = error_demo
 
 # For local execution only (not on Spaces)
 if __name__ == "__main__":