fix none

app.py

@@ -2391,6 +2391,8 @@ with demo:
                 image_plot = ImagePrompter(show_label=True, elem_id="image_plot", interactive=False, label="NCUT spectral-tSNE")
                 image_slider = gr.Slider(0, 100, step=1, label="Image Index", value=0, elem_id="image_slider", interactive=True)
                 def update_image_prompt(image_slider, output_gallery):
+                    if output_gallery is None:
+                        return gr.update(value=None, interactive=False)
                     if len(output_gallery) == 0:
                         return gr.update(value=None, interactive=False)
                     image_idx = int(image_slider)