AttributeError: 'NoneType' object has no attribute 'supportsService' about unoserver HOT 5 CLOSED

# unoserver
INFO:unoserver:Starting unoserver.
INFO:unoserver:Command: libreoffice --headless --invisible --nocrashreport --nodefault --nologo --nofirststartwizard --norestore -env:UserInstallation=file:///tmp/tmprvf8kqu5 --accept=socket,host=127.0.0.1,port=2002,tcpNoDelay=1;urp;StarOffice.ComponentContext
INFO:unoserver:Server PID: 33008

# unoconvert BookmarkService.csv BookmarkService.ods
INFO:unoserver:Starting unoconverter.
INFO:unoserver:Opening BookmarkService.csv
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/unoserver/converter.py", line 173, in convert
    import_type = get_doc_type(document)
  File "/usr/local/lib/python3.9/site-packages/unoserver/converter.py", line 43, in get_doc_type
    if doc.supportsService(t):
AttributeError: 'NoneType' object has no attribute 'supportsService'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/bin/unoconvert", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.9/site-packages/unoserver/converter.py", line 276, in main
    result = converter.convert(
  File "/usr/local/lib/python3.9/site-packages/unoserver/converter.py", line 225, in convert
    document.close(True)
AttributeError: 'NoneType' object has no attribute 'close'

# libreoffice --headless --convert-to ods BookmarkService.csv 
Error: source file could not be loaded

# unoconv --verbose --output=BookmarkService.ods BookmarkService.csv 
Input file: BookmarkService.csv
unoconv: UnoException during import phase:
The document 'file:///opt/test/BookmarkService.csv' could not be opened.