[fetchStore] Abortable fetch

[techniq]

• https://developer.mozilla.org/en-US/docs/Web/API/AbortController
• https://developers.google.com/web/updates/2017/09/abortable-fetch
• https://javascript.plainenglish.io/canceling-javascript-async-tasks-with-abortcontroller-acda9f67f7e7