This PR makes a change to the Worker.terminate() when called if the
kHandler is null. Before this pull request it was returning undefined,
but the API is expecting a promise. With the changes in this PR if
terminate is called a Promise.resolve() is returned, unless a callback
is passed in which case the old behavior stays (returns undefined).
PR-URL: https://github.com/nodejs/node/pull/28370
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
