Registering customization hooks via --require results in double registration

[Flarna]

The current recommendation to install customization hooks is to use --import.

But --import is still marked as experimental therefore not the preferred thing to use in production.

If I use the stable alternative --register the loader hooks are installed twice.

Easy to reproduce:

// loader.mjs
export async function resolve (specifier, context, parentResolve) {
    console.log('execArgv', process.execArgv);
	return await parentResolve(specifier, context);
}

// register.js
const { register } = require('node:module');
const { pathToFileURL } = require('node:url');

const url = pathToFileURL('./loader.mjs');

console.log('registering', url.href);
register(url);

// main.mjs
console.log("hello");

run with --require results in

node --require ./register.js  main.mjs  
registering file:///C:/work/node-double-loader/loader.mjs
registering file:///C:/work/node-double-loader/loader.mjs
execArgv [ '--require', './register.js' ]
execArgv [ '--require', './register.js' ]
hello

run with --import:

registering file:///C:/work/node-double-loader/loader.mjs
execArgv [ '--import', './register.js' ]
hello

I guess the --require argument gets forwarded to the internal Worker (along with env and other command line args) and in contrast to --import this seems to have an effect.

Not sure if the problem is the different behavior of --require vs --import in Worker.

But in general I think we should not blindly forward and command line args to the internal hooks worker.

Edit: Thinking once more I think we should forward env/--require/... configs to the internal worker. People migth want to get e.g. Otel into this thread to capture traces.