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

Inizia con il riproduttore main.py ed esegui mypy sui casi TypedDict e TypeVar, confrontando l'output di reveal_type per .get. Traccia il percorso del controllo dei tipi per una chiamata a .get su un TypeVar vincolato a TypedDict; il lavoro è completato quando il caso TypeVar rivela Union[list[str], None] invece di object.