Update demo.py

demo.py

@@ -94,6 +94,9 @@ def visualize_gaze_multi(face_boxes, gaze_points, image=None, show_plot=True):
 
 @spaces.GPU(duration=15)
 def process_image(input_image):
+    if input_image is None:
+        return None, ""
+        
     try:
         # Convert to PIL Image if needed
         if isinstance(input_image, np.ndarray):