Unsoundness with Pick and union subtyping

test.ts

declare function pick<T,F extends keyof T> (obj: T, fields: F[]): Pick<T, F>;

type User = {
    id: number,
    email: string,
    active: boolean,
};

function ok(u: User) {
    const a = pick(u, ['id', 'email']);
    console.log(a.id);
    console.log(a.active);  // <-- compile-time error (good)
}

function bad(u: User) {
    const fields: ('id' | 'email' | 'active')[] = ['id', 'email'];
    const a = pick(u, fields);
    console.log(a.id);
    console.log(a.active);  // <-- runtime error (bad)
}