Make einfo compatible with inspect (fixes #176)

[mrcljx]

Libraries like sentry or better-exceptions will fail while traversing exception chains with getframeinfo like this:

AttributeError: 'Traceback' object has no attribute 'f_lineno'

As mentioned in #176, we can not inherit from types.Traceback and friends, but it's possible to override __class__ which will make the isinstance check pass. This is also used internally by Python's unittest.mock module.

    @property
    def __class__(self):
        if self._spec_class is None:
            return type(self)
        return self._spec_class

An alternative approach could be to use a meta class and implement __subclasscheck__ ¹, but that felt too involved.

Footnotes

1. https://docs.python.org/3/reference/datamodel.html#class.__subclasscheck__ ↩

[auvipy]

please check the test failures in the CI

[auvipy]

can you please rebase?