Feature Request: Support for {@const} Inside <svelte:boundary>

[brandonbloom]

Describe the problem

I'd like to be able to write some code like this:

          {#each things as thing}
            <svelte:boundary>
              {@const x = someComplexFunction(thing)}

But I get this error:

`{@const}` must be the immediate child of `{#snippet}`, `{#if}`, `{:else if}`, `{:else}`, `{#each}`, `{:then}`, `{:catch}`, `<svelte:fragment>` or `<Component>`
https://svelte.dev/e/const_tag_invalid_placementsvelte(const_tag_invalid_placement)

I generally get understand the restrictions on @const, but being able to use it inside an error boundary seems appropriate as someComplexFunction may fail.

Describe the proposed solution

It should be possible to use @const inside a svelte:boundary

Importance

would make my life easier