Unsupported operand types for + ("list[None]" and "list[str]")

[randolf-scholz]

To Reproduce

from typing import Iterable

def prod[T](iter1: Iterable[T]) -> Iterable[tuple[T]]:
    return ((x,) for x in iter1)

x: list[str] = ["a", "b", "c"]
prod([None] + x)  # false positive [operator]

https://mypy-play.net/?mypy=master&python=3.12&gist=390f48f0541325d872d9cb419e3a5f20

[randolf-scholz]

Basically a duplicate of #19304, but the origin of the error is different (seeing how #19304 is fixed with #19399, but this one isn't)