cannot unpack non-iterable NoneType object

[Jandown]

Traceback (most recent call last):
File "E:\AI\MinerU-webui-main\python\lib\site-packages\gradio\queueing.py", line 624, in process_events
response = await route_utils.call_process_api(
File "E:\AI\MinerU-webui-main\python\lib\site-packages\gradio\route_utils.py", line 323, in call_process_api
output = await app.get_blocks().process_api(
File "E:\AI\MinerU-webui-main\python\lib\site-packages\gradio\blocks.py", line 2043, in process_api
result = await self.call_function(
File "E:\AI\MinerU-webui-main\python\lib\site-packages\gradio\blocks.py", line 1590, in call_function
prediction = await anyio.to_thread.run_sync( # type: ignore
File "E:\AI\MinerU-webui-main\python\lib\site-packages\anyio\to_thread.py", line 56, in run_sync
return await get_async_backend().run_sync_in_worker_thread(
File "E:\AI\MinerU-webui-main\python\lib\site-packages\anyio_backends_asyncio.py", line 2505, in run_sync_in_worker_thread
return await future
File "E:\AI\MinerU-webui-main\python\lib\site-packages\anyio_backends_asyncio.py", line 1005, in run
result = context.run(func, *args)
File "E:\AI\MinerU-webui-main\python\lib\site-packages\gradio\utils.py", line 865, in wrapper
response = f(*args, **kwargs)
File "E:\AI\MinerU-webui-main\webui.py", line 222, in pdf_parse
[markdown_content,file_path] = pdf_parse_main(target_pdf_path,progress)
TypeError: cannot unpack non-iterable NoneType object