That type won't help if you're unpacking like `user, err = get_user(user_id)`. Both values will be nullable and the type-checker won't understand that `user` is not None if `err` is None
Go can be `tuple[User | None, Exception | None]` or `tuple[User, Exception | None]`, depending on whether you're returning a pointer. But yea, Go's approach has its warts. Like if you aren't returning a pointer then you need to return the zero value (e.g. `User{}`) even when returning an error
I've also seen APIs that allow returning both error and a value ("something went wrong, but here is a fallback or something") which are of course extremely confusing given the usual style.