[@sentry/sveltekit 11] Build fails with "ReferenceError: cp is not defined" when sentrySvelteKit() is in the Vite plugins (adapter-vercel) #25113

Is there an existing issue for this?

I searched the issues for cp is not defined and related SvelteKit build errors, and found nothing.

How do you use Sentry?

Sentry SaaS (sentry.io)

Which SDK are you using?

@sentry/sveltekit

SDK Version

11.4.0 (also seen on 11.0.0). 10.x builds fine with the same project and config.

Framework Version

@sveltejs/kit 2.70.3, svelte 5.57.1, vite 7.3.6, rollup 4.59.0, @sveltejs/adapter-vercel 6.3.4, Node 24.13.1

Steps to Reproduce

1. A SvelteKit app on @sveltejs/adapter-vercel, upgraded from @sentry/sveltekit 10.x to 11.4.0.
2. vite.config.ts (the 11.x import path):

   import { sentrySvelteKit } from '@sentry/sveltekit/vite';
   export default defineConfig({
     plugins: [
       sentrySvelteKit({ org: '…', project: '…', authToken: process.env.SENTRY_AUTH_TOKEN }),
       sveltekit()
     ]
   });

3. vite build

Expected Result

The build succeeds, as it does on 10.x.

Actual Result

Vite and Rollup finish, then SvelteKit's post-build analyse step crashes while importing a server chunk:

ReferenceError: cp is not defined
    at file:///…/.svelte-kit/output/server/chunks/node.js:26:18
    at ModuleJob.run (node:internal/modules/esm/module_job:439:25)
    at async node:internal/modules/esm/loader:643:26
    at async analyse (…/@sveltejs/kit/src/core/postbuild/analyse.js:47:19)
    at async MessagePort.<anonymous> (…/@sveltejs/kit/src/utils/fork.js:23:16)

The generated chunk keeps node:child_process as a side-effect-only import, but still references the binding:

import "node:child_process";
import "node:crypto";
import * as fssync from "node:fs";
import * as path from "node:path";
import "node:stream";
import "node:util";
// … SvelteKit's shared-server env exports …
const node = /* @__PURE__ */ Object.freeze(/* @__PURE__ */ Object.defineProperty({
  __proto__: null,
  child_process: cp,   // <- `cp` is never declared
  crypto,
  fs: fssync,
  path,
  stream,
  util
}, Symbol.toStringTag, { value: "Module" }));

The chunk's source map lists only @sveltejs/kit/src/runtime/shared-server.js. No importer uses the node export; they import only SvelteKit's public_env and private_env from this chunk.

What I narrowed down

Every build below used the same project and the same lockfile, with VERCEL=1:

So the failure appears whenever sentrySvelteKit() is in the plugin list, whichever of its features are switched off. Source maps on their own are not the cause.

Additional Context

We're staying on 10.x until this is fixed. Happy to test a patched build. I can't share the app itself, but I can try particular options or provide more of the generated output.