Catch MRO error when applying missing hints feature.

[doranid]

Steps

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Description

This fixes #4687.
Missing type hints won't fail hard anymore when applied to an instance with an MRO with duplicated names.

Type of Changes

	Type
✓	🐛 Bug fix

Related Issue

Closes #4687

[coveralls]

Coverage increased (+0.01%) to 92.053% when pulling c5b66fc on doranid:fix_mro into 708527d on PyCQA:main.

[Pierre-Sassoulas]

I had a feeling this was something we had to fix in astroid, but no tests seems to fail when simply catching the exception. Do you have an opinion @cdce8p ?

[Pierre-Sassoulas]

Thank you for this fix :) ! Could you add the example you gave in the issue in tests/functionals/r/regression/regression_mro_error.py ?

# pylint: disable=missing-docstring,pointless-statement,useless-object-inheritance


class Klass(object, object):
    def get(self):
        self._non_existent_attribute [no-member]

If it's not working we'll have to modify astroid and release a new version.

[doranid]

Hey, I added the required tests. Thanks :)

[Pierre-Sassoulas]

The test was failing because you're probably on python 3.7 and we do not check the column in the tests for python 3.7 because the ast got different and better in 3.8. Thanks for fixing this crash, you're helping us release 2.9.4 faster !

[Pierre-Sassoulas]

Congratulation on becoming a pylint contributor, especially on such an important issue, the fast crash fixes after a new release are very stressful as maintainer <3 !