Customization hooks / ESM loaders reports importing JSON warning on commonjs modules

[hyrious]

Version

v22.1.0

Platform

Darwin MAGIT00999.local 23.5.0 Darwin Kernel Version 23.5.0: Wed May 1 20:09:52 PDT 2024; root:xnu-10063.121.3~5/RELEASE_X86_64 x86_64

Subsystem

No response

What steps will reproduce the bug?

Prepare the 3 files:

// register.mjs
import { register } from 'module'
import { readFile } from 'fs/promises'

export async function load(url, context, nextLoad) {
  const result = await nextLoad(url, context)
  if (result.format === 'commonjs') {
    // https://nodejs.org/api/module.html#:~:text=result.source%20%3F%3F%3D%20await%20readFile(new%20URL(result.responseURL%20%3F%3F%20url))%3B
    result.source ??= await readFile(new URL(result.responseURL ?? url))
  }
  return result
}

register('./register.mjs?' + Date.now(), import.meta.url)

// test.js
require('./package.json')

// package.json
{}

Then execute:

> node --import ./register.mjs test.js
(node:5296) ExperimentalWarning: Importing JSON modules is an experimental feature and might change at any time
(Use `node --trace-warnings ...` to show where the warning was created)

How often does it reproduce? Is there a required condition?

It happens only with:

result.source ??= await readFile(new URL(result.responseURL ?? url));

If it does not handle commonjs files like this, it won't happen.

What is the expected behavior? Why is that the expected behavior?

require(json_file) in commonjs modules should not emit this warning.

What do you see instead?

It emits warning

(node:5296) ExperimentalWarning: Importing JSON modules is an experimental feature and might change at any time

Additional information

No response

[benjamingr]

@nodejs/loaders @joyeecheung

[joyeecheung]

Likely a regression from #47999