this is awesome, been looking forward to using async/await in production node.js without transpilers!
In other words, you've been able to for a while now, you've just chosen constraints that don't let you, so your response isn't very honest.
In Koa, you're inside one big top-level async function so all of your business code is as well. Any errors you have are async and bubble up.
Async/await is something that made Javascript concurrency not just bearable but better than the day-to-day code of other languages I use.