Rename ErrInternal to ErrFatal and use abort

[ankur22]

Fatal better describes the error, and it will help distinguish from other internal errors (which are generally temporary). Fatal is a permanent error, which should end the whole test run not just the current iteration. If we ran the same iteration again then there's a 100% chance that we will run into the same error, e.g. trying to work with an unimplemented API is a Fatal error.

Here are two test scripts I used to test this change:

When ran with xk6 run -i 10 examples/test.js before the change, this test will iterate 10 times, failing each iteration. After the change it will stop on the first iteration.

import { chromium } from 'k6/x/browser'

export default async function () {
  const browser = chromium.launch({headless: false})
  const context = browser.newContext()
  context.cookies()
}

This test will stop the whole test run before the change and after the change.

import { chromium } from 'k6/x/browser'

export default async function () {
  const browser = chromium.launch({headless: false})
  const context = browser.newContext()
  context.setExtraHTTPHeaders()
}

[ka3de]

Thanks for refactoring this after initial discussions @ankur22 ! 👍
I added just one question/comment.

[ka3de]

Some minor comments. Feel free to accept or discard at your discretion.
LGTM.

[inancgumus]

Nice job 👏