Function returnOnAbort

Waits for signal to abort, resolves with signal.reason when it is aborted. The wait can be cancelled by providing a second signal - cancelSignal. When cancelSignal is cancelled, promise rejects with AbortedError

Any listeners added on both signal and cancelSignal are always removed by the time the promise is settled - no leaks

Note that this function is curried - returnOnAbort(signal)(cancelSignal) instead of returnOnAbort(signal, cancelSignal). This is to encourage cleanup of listeners when using it with select. Compare:

Listener is removed once select completes:

await select({ 
 aborted: returnOnAbort(mySignal),
 someOtherOp: something,
})
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Listener is not removed until mySignal aborts:

await select({ 
 aborted: returnOnAbort(mySignal)(),
 someOtherOp: something,
})
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In former we pass (cancelSignal?: AbortSignal) => Promise<unknown>, which allows cancellation via cancelSignal. In later we pass Promise<unknown>, which cannot be cancelled