fix issues

app.py

@@ -66,25 +66,22 @@ def create_app():
                         file_types=[".npy"]
                     )
 
-                et_viewer = Rerun(streaming=False)
-
                 with gr.Row():
                     visualize_btn = gr.Button("Visualize")
+                    visualize_btn.click(
+                        process_et_files,
+                        inputs=[traj_file, char_file],
+                        outputs=[et_viewer]
+                    )
 
                 with gr.Row():
-                    et_viewer.render()
+                    et_viewer = Rerun(streaming=False)
 
                 def process_et_files(traj_file, char_file):
                     if traj_file is None or char_file is None:
                         return None
                     return visualize_et_data(traj_file.name, char_file.name)
 
-                visualize_btn.click(
-                    process_et_files,
-                    inputs=[traj_file, char_file],
-                    outputs=[et_viewer]
-                )
-
     return demo