Calls to `.get` on TypeVars bound to TypedDict narrow to `object`

Bug Report

When using dict.get to access specific members of TypeVar entries bound to TypedDict, mypy always narrows the type to object where, without the TypeVar, we expect the union of the underlying type and None.

To Reproduce

from typing import TypedDict, TypeVar

class MyDict(TypedDict):
    my_attributes: list[str]

def take_my_dict(d: MyDict):
    reveal_type(d['my_attributes'])
    reveal_type(d.get('my_attributes'))

MyDictT = TypeVar('MyDictT', bound=MyDict)

def take_my_typevar(d: MyDictT):
    reveal_type(d['my_attributes'])
    reveal_type(d.get('my_attributes'))

Expected Behavior

   main.py:7: note: Revealed type is "builtins.list[builtins.str]"
   main.py:8: note: Revealed type is "Union[builtins.list[builtins.str], None]"
   main.py:13: note: Revealed type is "builtins.list[builtins.str]"
   main.py:14: note: Revealed type is "Union[builtins.list[builtins.str], None]"

Actual Behavior

   main.py:7: note: Revealed type is "builtins.list[builtins.str]"
   main.py:8: note: Revealed type is "Union[builtins.list[builtins.str], None]"
   main.py:13: note: Revealed type is "builtins.list[builtins.str]"
=> main.py:14: note: Revealed type is "builtins.object"

Your Environment

• Mypy version used: 1.8.0
• Mypy command-line flags: n/a
• Mypy configuration options from mypy.ini (and other config files): n/a
• Python version used: 3.12

Beginne mit dem Reproducer main.py und führe mypy für die TypedDict- und TypeVar-Fälle aus, wobei du die reveal_type-Ausgabe für .get vergleichst. Verfolge den Typprüfpfad für einen .get-Aufruf bei einem an TypedDict gebundenen TypeVar; abgeschlossen ist die Aufgabe, wenn der TypeVar-Fall Union[list[str], None] statt object ergibt.