`list.sort()` fails to detect type issue

This code is not failing under mypy:

[2, None].sort()

Interestingly, it fails on ty:

error[invalid-argument-type]: Argument to bound method `list.sort` is incorrect
 --> toto.py:1:1
  |
1 | [None, 2].sort()
  | ^^^^^^^^^^^^^^^^ Argument type `None | int` does not satisfy upper bound `SupportsDunderLT[Any] | SupportsDunderGT[Any]` of type variable `SupportsRichComparisonT`
  |
info: Type variable defined here
   --> stdlib/_typeshed/__init__.pyi:107:1
    |
107 | SupportsRichComparisonT = TypeVar("SupportsRichComparisonT", bound=SupportsRichComparison)  # noqa: Y001
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |

Found 1 diagnostic

Reproduce the reported difference between mypy and ty with [2, None].sort(), then inspect the list.sort typing and the referenced stdlib/_typeshed/__init__.pyi definition. Determine the expected diagnostic and add regression coverage for the case, with the behavior made consistent with that expectation.