related to https://twitter.com/timkevinoxley/status/1309169428668579841

1-events-on.test.js

const Emitter = require('events')
const emitter = new Emitter()

// Currently, (Node v14.12.0) this just prints 'iterating', waits a moment, then silently exits 0.
// But adding at least one event triggers the full flow of: iterating, caught, finally, rejected
// thinking maybe throw() should call errorHandler?
;(async () => {
    const it = Emitter.on(emitter, 'test')
    setTimeout(() => {
        // emitter.emit('test') // uncomment to trigger full error flow
        it.throw(new Error('expected'))
    }, 100)
    try {
        console.log('iterating')
        for await (const t of it) {
            console.log({ t })
        }
        console.log('iterated')
    } catch (err) {
        console.log('caught err', err)
        throw err
    } finally {
        console.log('finally')
    }
    console.log('ending...')
})().then(() => {
    console.log('done')
}, (err) => {
    console.log('rejected with', err)
})

2-async-generator.test.js

const wait = (ms) => new Promise((resolve) => setTimeout(resolve, ms))

async function* T() {
    await wait(500)
    yield 1
    await wait(500)
    yield 2
}

// this logs: iterating, { t: 1 }, iterated, finally, ending..., done
// but now with a bonus UnhandledPromiseRejectionWarning (need to attach .catch to it.throw to handle :/)
// note: according to spec this *should* wait for first yield, that's fine.
;(async () => {
    const it = T()
    setTimeout(() => {
        it.throw(new Error('expected'))
    }, 100) // happens before first yield
    try {
        console.log('iterating')
        for await (const t of it) {
            console.log({ t })
        }
        console.log('iterated')
    } catch (err) {
        console.log('caught err', err)
        throw err
    } finally {
        console.log('finally')
    }
    console.log('ending...')
})().then(() => {
    console.log('done')
}, (err) => {
    console.log('rejected with', err)
})