(🐞) Bad error message when using unbound ParamSpec in a Callable

[KotlinIsland]

from typing import ParamSpec, Callable

P = ParamSpec("P")
a: Callable[P, None]  # error: The first argument to Callable must be a list of types, parameter specification, or "..."

playground

[flaeppe]

Found a similar output in #13403

[ilevkivskyi]

This example works on master, likely fixed by #15837 (note this declares a generic function that ignores its arguments, consistently with how regular type variables work).