mypy crashes with python 3.14 within argparse #19150

class AugmentedHelpFormatter(argparse.RawDescriptionHelpFormatter):
    def __init__(self, prog: str, **kwargs: Any) -> None:
        super().__init__(prog=prog, max_help_position=28, **kwargs)

  File "venv314/lib/python3.14/site-packages/mypy/__main__.py", line 15, in console_entry
    main()
    ~~~~^^
  File "venv314/lib/python3.14/site-packages/mypy/main.py", line 88, in main
    sources, options = process_options(args, stdout=stdout, stderr=stderr, fscache=fscache)
                       ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "venv314/lib/python3.14/site-packages/mypy/main.py", line 1055, in process_options
    parser.add_argument(
    ~~~~~~~~~~~~~~~~~~~^
        "--enable-incomplete-feature",
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<2 lines>...
        help="Enable support of incomplete/experimental features for early preview",
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/data/.pyenv/versions/3.14.0b1/lib/python3.14/argparse.py", line 1562, in add_argument
    formatter = self._get_formatter()
  File "/data/.pyenv/versions/3.14.0b1/lib/python3.14/argparse.py", line 2729, in _get_formatter
    return self.formatter_class(
           ~~~~~~~~~~~~~~~~~~~~^
        prog=self.prog,
        ^^^^^^^^^^^^^^^
        prefix_chars=self.prefix_chars,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        color=self.color,
        ^^^^^^^^^^^^^^^^^
    )
    ^
TypeError: AugmentedHelpFormatter.__init__() got an unexpected keyword argument 'prefix_chars'.)