AsyncLocalStorage support

https://nodejs.org/api/async_hooks.html#async_hooks_class_asynclocalstorage

we should run every request in it so that errors can be traced to the original req/res even if they were called in a different event loop. this will also allow us to not pass req/res/ctx to track sources of errors.

the store would be ctx

const ctx = app.asyncLocalStorage.getStore()
if (ctx) // ...

[dmitriiivashko]

You can always create a middleware that wraps the next middleware in async storage run. There’s no need to build this into koa core and force everyone to use this functionality

[jkomyno]

I agree, with @dmitriiivashko and @hauau. @jonathanong, have you created a custom middleware as suggested? If so, can this issue be closed?