unhandledRejection misfires a lot

[ChALkeR]

import assert from 'node:assert'

globalThis.addEventListener('unhandledrejection', (e) => {
  console.error('unhandled rejection:', e.reason)
})

const asyncFunction = async (name) => {
  throw new Error(`this function rejects: ${name}`)
}

export const AssertBased = {
  async test(ctrl, env, ctx) {
    assert.rejects(async () => asyncFunction('A'))
  },
}

export const Manual = {
  async test(ctrl, env, ctx) {
    const error = await Promise.resolve().then(function () {
      return asyncFunction('B')
    }).then(function () {
      return null
    }).catch(function (e) {
      return e
    })

    // console.log('Got this error:', error)
  },
}

export const TryCatch = {
  async test(ctrl, env, ctx) {
    try {
      await Promise.resolve('C').then(asyncFunction)
    } catch (error) {
      // console.log('Got this error:', error)
    }
  },
}

In all these cases, A, B, and C are logged as unhandled rejections, while they are, in fact, handled.

[jasnell]

Yep, we've needed to refine the unhandled rejection book keeping for a while now.

[ChALkeR]

As a work-around, unhandledrejection + rejectionhandled + setTimeout(0) works fine

A fix could like like that here - just delay all unhandledrejection fires until microtask queue completes and then fire those that weren't handled until they are fired