Promise Timeout

Requirements

• Implement promiseTimeout(value, timeoutMs), returning a new Promise. Accept a Promise, thenable, or ordinary value using Promise.resolve assimilation.
• If the input fulfills before the timeout callback runs, resolve with the same value. If it rejects first, reject with the identical reason, even when that reason is not an Error.
• If the timeout callback wins, reject with an Error named TimeoutError whose message is Promise timed out. Later input settlement must not change the result.
• Clear the timer when input settles first. Always attach input fulfillment and rejection handlers, so a rejection after timeout is still handled. This wrapper cannot cancel the original operation.
• timeoutMs must be a finite number from 0 through 2147483647 inclusive. Invalid timeouts return a rejected Promise with RangeError instead of throwing synchronously. Fractional delays use native timer behavior.
• Already settled promises and immediate values win against a zero-delay timer because promise reactions run before the timer callback. Do not use Promise.race; manage the timer and settlement handlers explicitly.

Examples

Input: await promiseTimeout(Promise.resolve("ready"), 1000)
Output: "ready"

Input: await promiseTimeout(new Promise(() => {}), 20)
Output: Rejects with TimeoutError: Promise timed out.