fix: preserve error stack trace in timer

[pius712]

when error occurred that made in callback function in timer,
error stack is missing.
So to prevent from missing error stack, I declared error from outer of timer callback.

[sindresorhus]

Can you show the stack trace before and after this change?

[pius712]

If run code below.

async function foo() {
    await bar();
}

async function bar() {
    await pTimeout(sleep(50), {milliseconds: 10})
}

async function sleep (ms: number) {
    return new Promise((res)=> {
        setTimeout(()=>{
            res('hi')
        }, ms)})
}
(async ()=>{
        await foo();
    })()

fixed version

TimeoutError: Promise timed out after 10 milliseconds
    at file:///myPath/node_modules/p-timeout/index.js:68:24
    at new Promise (<anonymous>)
    at pTimeout (file:///myPath/node_modules/p-timeout/index.js:48:28)
    at file:///myPath/src/index.ts:11:11
    at Generator.next (<anonymous>)
    at file:///myPath/src/index.ts:7:71
    at new Promise (<anonymous>)
    at __awaiter (file:///myPath/src/index.ts:3:12)
    at bar (file:///myPath/src/index.ts:17:12)
    at file:///myPath/src/index.ts:6:11

prev version shows

TimeoutError: Promise timed out after 10 milliseconds
    at Timeout._onTimeout (file:///MyPath/node_modules/p-timeout/index.js:90:12)
    at listOnTimeout (node:internal/timers:559:17)
    at processTimers (node:internal/timers:502:7)

[pius712]

prev version doesn't show any information about caller, because they made in timer callback function that saved in timers queue in terms of event loop. But fixed version can show it because error is made before timer, so capture trace.