unload fail，error as bellow

[jasoncow007]

Traceback (most recent call last):
File "D:\sd-webui-aki-v4\py310\lib\site-packages\gradio\routes.py", line 422, in run_predict
output = await app.get_blocks().process_api(
File "D:\sd-webui-aki-v4\py310\lib\site-packages\gradio\blocks.py", line 1323, in process_api
result = await self.call_function(
File "D:\sd-webui-aki-v4\py310\lib\site-packages\gradio\blocks.py", line 1051, in call_function
prediction = await anyio.to_thread.run_sync(
File "D:\sd-webui-aki-v4\py310\lib\site-packages\anyio\to_thread.py", line 31, in run_sync
return await get_asynclib().run_sync_in_worker_thread(
File "D:\sd-webui-aki-v4\py310\lib\site-packages\anyio_backends_asyncio.py", line 937, in run_sync_in_worker_thread
return await future
File "D:\sd-webui-aki-v4\py310\lib\site-packages\anyio_backends_asyncio.py", line 867, in run
result = context.run(func, *args)
File "D:\sd-webui-aki-v4\extensions\unload-button\scripts\unload_button.py", line 16, in unload
sd_hijack.model_hijack.undo_hijack(shared.sd_model)
File "D:\sd-webui-aki-v4\modules\sd_hijack.py", line 206, in undo_hijack
if type(m.cond_stage_model) == xlmr.BertSeriesModelWithTransformation:
AttributeError: 'NoneType' object has no attribute 'cond_stage_model'
提示：Python 运行时抛出了一个异常。请检查疑难解答页面。