Thank you for your review! I have merged your suggestions.
I also updated eslintrc to use arrow-body-style rule.
https://eslint.org/docs/rules/arrow-body-style

Could a similar change be applied to no-lifecycle-after-await so it also supports script setup?

Sounds like a valid improvement. Could you please open an issue for that? And maybe you'd like to implement that change? It should be quite similar to this PR.

No. Since the changes in Vue 3.2, there is no problem in doing it after await in script setup.

@FloEdelmann Added #2291

@ota-meshi I'm using vue@3.3.4, but I still get the console warning Lifecycle injection APIs can only be used during execution of setup(). If you are using async setup(), make sure to register lifecycle hooks before the first await statement. at runtime when using onMounted after await. Is that something different?

You can check it on SFC Playground. You can see that the compilation result of await doSomething() looks like this:

;(
  ([__temp,__restore] = _withAsyncContext(() => doSomething())),
  await __temp,
  __restore()
)

__restore() should now allow you to use lifecycle methods and others then defineExpose. If it doesn't work, I think it's a bug in Vue.

SFC Playground:

https://play.vuejs.org/#eNqNUk1rwkAQ/SvLXkxAotabpEJbPLTQVqrHvYRkjGuT3WU/VJD8984kmlaopadk5r03vHmzJ/5gTLIPwGc8dbmVxjMHPpi5ULI22nr2pGvDNlbXbJCMqCD6QKh01PGRiYWH2lSZB6wYS1fBGVAO5ikJ5mmrw0/fJ3kv4UPuXa7VRpbJzmmFXk40RvAcZbIC+2681MoJPmMtQlhWVfrw0va8DTC89PMt5J+/9HfuSD3BlxYc2D0I3mM+syX4Dl6s3uCI/z1Y6yJUyP4D/ACnq0AeO9pjUAXa/sFr3T63iUpVrt3i6DGIy1JklJhNyxccE6bEbq3+bXeaTFudUA2meLnO7WOemFavOigPBWvOV+3OKVSPRFHM7ufIxZvgXpBUuowG9Vk2GcSsiUmQHTLpWaFXuga/xbWitv3POXf9nE1QOS15PQp1Fs1bxRQc2BKtSgcR3o5m4lprWYMOnjpDNhmPx3GMMdx8lZTN1asjAm++AK0DBNA=

Note that your own implementation of async setup(props) will not do this. This only applies to <script setup>.

Ok, that's interesting. The warning I saw must be caused by something else then. Thank you for the explanation!