/**
 * `work`, or a rejection named TimeoutError once `ms` has passed. An abort signal reaches a request only once
 * fetch starts; the session token and the device proof are awaited before that, so a deadline on the whole
 * promise is what bounds a read. An answer after it is dropped.
 */
export const withinDeadline = <T,>(work: Promise<T>, ms: number | undefined, what = 'read'): Promise<T> => {
    if (ms === undefined) return work;
    return new Promise<T>((resolve, reject) => {
        const timer = setTimeout(() => reject(Object.assign(new Error(`${what} timed out`), { name: 'TimeoutError' })), ms);
        work.then(
            (value) => { clearTimeout(timer); resolve(value); },
            (error) => { clearTimeout(timer); reject(error); },
        );
    });
};