Fix step error handling and wire up error_box

app.py

@@ -38,9 +38,9 @@ def _save_to_disk(img):
     if img is None:
         return gr.skip()
     
-    os.makedirs("/tmp/gradio_outputs", exist_ok=True)
+    os.makedirs("./outputs", exist_ok=True)
     ts = datetime.now().strftime("%Y%m%d_%H%M%S")
-    path = f"/tmp/gradio_outputs/step1_result_{ts}.png"
+    path = f"./outputs/step1_result_{ts}.png"
     img.save(path)
     return path