Exported functions don't work on async components

[ottomated]

Describe the bug

This component is broken:

<script>
  export function get_name() {
    return 'world';
  }
  // Comment this out and it works
  await Promise.resolve();
</script>

because it defines get_name inside the async function $$body, but calls $.pop in the actual component function. This causes a ReferenceError.

Reproduction

REPL

Logs

Uncaught ReferenceError: get_name is not defined

  in <unknown>
  in __wrapper.svelte
    get get_name playground:output:4786
    get playground:output:2591
    App playground:output:4809

System Info

svelte 5.38.2

Severity

blocking an upgrade

[dummdidumm]

I believe @Rich-Harris wanted to make it illegal to export instance variables from async components for this reason. Either we do that for all, or we only do it for the statements after the first await.

[ottomated]

Could they be deferred until after the component mounts, and then language-tools marks them as optional if they're on an async component?