new URL(url, import.meta.url) pattern broken for javascript modules in production

[shamrin]

new URL(url, import.meta.url) pattern broken for .js assets in production

// main.js
function getJsUrl(name) {
  return new URL(`./sub/${name}.js`, import.meta.url).href
}
console.log(getJsUrl('a'))

// sub/a.js
export default class a {
  name = 'a'
}

The above works fine in npm run dev:

https://vitejs-vite-ohe6tf--5173.local.webcontainer.io/sub/a.js

However, it's broken in npm run build && npm run preview, showing class .toString():

https://vitejs-vite-ohe6tf--4173.local.webcontainer.io/class%20a%7Bconstructor()%7Bl(this,%22name%22,%22a%22)%7D%7D

https://vitejs.dev/guide/assets.html#new-url-url-import-meta-url

Reproduction

https://stackblitz.com/edit/vitejs-vite-ohe6tf?file=main.js

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (4) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 16.14.2 - /usr/local/bin/node
    Yarn: 1.22.10 - /bin/yarn
    npm: 7.17.0 - /bin/npm
  npmPackages:
    vite: ^3.0.1 => 3.0.2 

Used Package Manager

npm

Logs

No response

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• The provided reproduction is a minimal reproducible example of the bug.