Error when handling normalised names for package extras

[mhentz]

I use a package that provides the extra async_s3. The underscore is how it's defined in the external package's setup.py. I prefer to use normalised names though, i.e. with hyphens, so in my requirements.txt I specify the extra as async-s3. Running the license check on my requirements file then raises an error that looks like this:

pkg_resources.UnknownExtra: foo-bar 0.0.1 has no such extra feature 'async-s3'

The source of the error is

Traceback (most recent call last):
  File "/path/to/site-packages/pkg_resources/__init__.py", line 2791, in requires
    deps.extend(dm[safe_extra(ext)])
                ~~^^^^^^^^^^^^^^^^^
KeyError: 'async-s3'

The error occurs in the deprecated package pkg_resources (importlib modules are the intended replacement; see https://setuptools.pypa.io/en/latest/pkg_resources.html) so this issue must presumably be resolved here.

Hope you find the time to help with this issue, thanks!

I am running Python 3.11.9 and liccheck version 0.9.2.