Minimal reproduction for a Vite SSR webworker build gap that survives the fix in #21963 (fix #21969).

npm install
npm run build          # uses vite.config.js
cat dist/entry.js

dist/entry.js contains, for the bundled CommonJS module's nested require("crypto"):

var crypto = __require("crypto");   // throwing stub under platform:'browser'

The __require runtime stub throws Calling \require` for "crypto" in an environment that doesn't expose the `require` function— so this crashes on Cloudflare Workers (workerd), where there is no globalrequire`. (In a framework build such as SvelteKit that evaluates the SSR output during build analysis, the build itself fails at this stub.)

esmExternalRequirePlugin() IS added by Vite for webworker SSR (PR #21963), but it is invoked with an empty external, so it converts nothing.

Pass the node builtins / resolved externals to the plugin:

npx vite build --config vite.config.fix.js
cat dist-fixed/entry.js

Now the nested require is converted to a real ESM import (works on workerd):

import * as m from "crypto";
// ...
var crypto = require_builtin_esm_external_require_crypto();  // -> m.default

So the fix is for Vite's webworker SSR wiring to call esmExternalRequirePlugin({ external: [...node builtins / resolved externals] }) instead of esmExternalRequirePlugin().