`UnhandledSchemeError` when dependency uses `node:assert` imports

What version of Next.js are you using?

11.1.2

What version of Node.js are you using?

14.17.6

What browser are you using?

ff

What operating system are you using?

linux

How are you deploying your application?

vercel

Describe the Bug

In a project which has micromark-util-events-to-acorn@1.0.1 as a dependency, i get the following error when running yarn dev:

Module build failed: UnhandledSchemeError: Reading from "node:assert" is not handled by plugins (Unhandled scheme).

Things to note about this package: it uses an export map with a “development” user condition, and node:assert is only used there, not in the exported production build.

Expected Behavior

No error.

To Reproduce

1. git clone https://github.com/stefanprobst/issue-next-webpack-node-imports.git
2. cd issue-next-webpack-node-imports
3. yarn && yarn add next@latest && yarn dev
4. open http://localhost:3000/
5. See error message

[balazsorban44]

Oh, interesting. The reproduction uses 11.1.2, but upgrading to latest does throw the error after all. 👀

It might be because the client-side code elimination tool isn’t able to recognize the module you are using is for server-only.

import fs from "node:fs"

export default function Home() {
  return null
}

export async function getStaticProps() {
  console.log(fs)
  return { props: {} }
}

This works as the code can be analyzed and Next.js will know where the node: import is being used.

Let’s reopen and investigate further.

[stefanprobst]

I’m still getting this error with next.js 12