TypedDict didn't raise unexpected key error

Question

According to the TypedDict documentation, the following code should raise:

error: Unexpected key 'director'

from typing import TypedDict

class Movie(TypedDict):
    name: str
    year: int

m: Movie = dict(
    name='Alien',
    year=1979,
    director='Ridley Scott')

But nothing happened. I can still query the "director" field. Why is that?

print(m["director"])

Ridley Scott