Disallow top-level await before defineExpose

[AndreasNasman]

Please describe what the rule should do:
The rule should notify when defineExpose is used after any top-level await. Doing so causes problems as described in this core Vue.js issue:
vuejs/core#4930

What category should the rule belong to?
[x] Warns about a potential error (problem)

Provide 2-3 code examples that this rule should warn about:

// Example 1
...
<script setup>
  ...
  const foo = { bar: 'baz' };
  await asyncOperation();
  defineExpose({ foo }); // `defineExpose` should be called before any top-level `await`.
  ...
</script>
...

// Example 2
...
<script setup>
  ...
  await asyncOperation();
  const foo = { bar: 'baz' };
  defineExpose({ foo }); // `defineExpose` should be called before any top-level `await`.
  ...
</script>
...

Additional context
The current workaround is to manually remember to place all awaits after defineExpose. Forgetting to do so leads to problems that are hard to debug. In the context of my examples, a JavaScript error would be thrown when foo is used (foo is not defined or similar) in some other component and it's unclear the source of the problem is actually in the component defining foo.

The problem seems challenging to fix in Vue.js itself:
vuejs/core#4930 (comment)

[AndreasNasman]

To clarify, this only happened in a production build – the development build worked fine – and was therefore extra hard to debug.

[FloEdelmann]

The rule vue/no-expose-after-await should already catch this case. It is currently uncategorized and has to be enabled manually. It will be added to all Vue 3 preset configs in the next major version: #1848

Could you please enable it manually and check whether it reports all problematic cases?

[AndreasNasman]

I scaffolded a new Vue project with npm init vue@latest and it seems to only work for regular script components taking expose as a setup parameter, not script setup that uses defineExpose.

I upgraded the ESLint and eslint-plugin-vue versions to the latest stable releases, 8.14.0 and 8.7.1 respectively, so it's present in the latest stable versions.

[FloEdelmann]

Thanks for testing! So the vue/no-expose-after-await rule should be adapted to also catch cases in <script setup>.