update app

app.py

@@ -156,10 +156,10 @@ ppt.save("output.pptx")
         ]
         subprocess.run(command)
 
-        return "Default slide generated after 3 attempts failed.", pptx_path, preview_image
+        return "Default slide generated after 3 attempts failed.", pptx_path
 
     except Exception as e:
-        return f"An error occurred: {str(e)}", None, None
+        return f"An error occurred: {str(e)}", None
     finally:
         # Cleanup temporary files
         files_before.add("output.pptx")