esrap 2.3.3: server codegen emits invalid JS when `@type` JSDoc on `export let` meets a `$:` declaration

Correction (edited shortly after filing): the trigger is esrap 2.3.3, not a Svelte version. The original text bisected over Svelte releases, which was confounded — each install resolved a different transitive esrap. Details below.

Describe the bug

With esrap 2.3.3, generate: 'server' emits syntactically invalid JavaScript when a /** @type {...} */ comment sits on an export let prop and the component also has a $: declaration.

The hoisted declaration for the reactive variable now has its declarator wrapped in parentheses, which is not legal after let:

// esrap 2.3.2 — valid
let /** @type {string} */
c;

// esrap 2.3.3 — invalid
let /** @type {string} */ (
c);

V8 rejects it with SyntaxError: Unexpected strict mode reserved word, oxc/rolldown with The keyword 'let' is reserved — since let cannot start a declaration here, it parses as an identifier reference, which is reserved in strict mode/modules.

generate: 'client' is unaffected, so this only surfaces in SSR builds.

Because svelte depends on esrap: ^2.2.9, a fresh npm install resolves 2.3.3 and any project of this shape starts failing to build with no change on its own side. sveltekit-superforms is one concrete path in: its package entry re-exports dist/client/SuperDebug.svelte as the default export, so the component enters the module graph from every import { superForm } from 'sveltekit-superforms' and fails to parse even though it is never rendered.

Reproduction

MinRepro.svelte:

<script>
	/** @type {string} */
	export let a = 'x';
	$: c = a;
</script>

{c}

import fs from 'node:fs';
import { compile } from 'svelte/compiler';

fs.writeFileSync(
	'out.mjs',
	compile(fs.readFileSync('MinRepro.svelte', 'utf8'), {
		generate: 'server',
		filename: 'MinRepro.svelte'
	}).js.code
);
// node --check out.mjs  ->  SyntaxError: Unexpected strict mode reserved word

Both ingredients are required, and the trigger is specifically @type. Removing the $: line, or using /** Docs. */, @param, @deprecated, @typedef, @returns, a non-JSDoc /* … */ block, or // comments, all produce valid output.

Version boundary

Pinning esrap through overrides with svelte held fixed, on a clean node_modules each time:

esrap	result
2.2.10 … 2.3.2	ok
2.3.3 (latest, published 2026-08-13)	broken

Independent of the Svelte version — 5.56.1 and 5.56.9 are both ok on esrap 2.3.2 and both broken on 2.3.3.

This may belong in sveltejs/esrap rather than here; filing where it surfaces.

Stack

svelte:                     5.56.9 (also reproduced on 5.56.1)
esrap:                      2.3.3  (2.3.2 and earlier are fine)
sveltekit-superforms:       2.30.2
@sveltejs/kit:              2.70.2
@sveltejs/vite-plugin-svelte: 7.3.0
vite:                       8.2.1 (rolldown 1.2.4)
typescript:                 6.0.2
node:                       22.18.0
npm:                        10.9.3
OS:                         macOS 26.5.2

Severity

annoyance — the compiler produces invalid output silently rather than erroring, so it surfaces as a bundler parse error in an unrelated node_modules file.