Update

app.py

@@ -162,7 +162,9 @@ class webui:
         self.demo = gr.Blocks()
 
     def main(self, image_path):
-        image = Image.open(image_path).convert('RGBA')
+        image = Image.open(image_path)
+        if image.mode != 'RGBA':
+            image = image.convert('RGBA')    
         #拡張子を取り除いたファイル名を取得
         image_name = os.path.splitext(image_path)[0]
         alpha = image.getchannel('A') if image.mode == 'RGBA' else None