Why does Visual Studio Code show that the type is NonNullableUserPropertyKeys = never?

Question

typescript

type NonNullablePropertyKeys<T> = {
    [P in keyof T]: null extends T[P] ? never : P;
  }[keyof T];

  type User = {
    name: string;
    email: string | null;
  };

  type NonNullableUserPropertyKeys = NonNullablePropertyKeys<User>;

Why is Visual Studio Code showing this type of NonNullableUserPropertyKeys = never?