False positive for optional class attribute

[CareF]

Bug description

"""test_lint.py"""
from typing import Optional

class Foo:
    """class Foo"""
    a: Optional[dict] = None
    def empty(self):
        """foo"""

    @classmethod
    def init(cls):
        """init"""
        if cls.a is None:
            cls.a = {}
        assert cls.a is not None
        assert isinstance(cls.a, dict)
        if cls.a is None:
            return
        cls.a[1] = 2
        _ = cls.a[1]
        _ = 1 in cls.a

Configuration

No response

Command used

pylint test_lint.py

Pylint output

************* Module test_lint
test_lint.py:19:8: E1137: 'cls.a' does not support item assignment (unsupported-assignment-operation)
test_lint.py:20:12: E1136: Value 'cls.a' is unsubscriptable (unsubscriptable-object)
test_lint.py:21:19: E1135: Value 'cls.a' doesn't support membership test (unsupported-membership-test)

------------------------------------------------------------------
Your code has been rated at 0.00/10 (previous run: 0.00/10, +0.00)

Expected behavior

All above errors should not be triggered by cls.a

Pylint version

pylint 3.2.5
astroid 3.2.2
Python 3.12.4 (main, Jun  6 2024, 18:26:44) [Clang 15.0.0 (clang-1500.3.9.4)]

OS / Environment

MacOS with homebrew

Additional dependencies

pylint 3.2.5
astroid 3.2.2
Python 3.12.4 (main, Jun  6 2024, 18:26:44) [Clang 15.0.0 (clang-1500.3.9.4)]