[BUG] Crash when Node starts from ESM module

[sla100]

When

Use @npmcli/config from ESM Nodejs code.

How

Current Behavior

TypeError: Cannot read property 'filename' of undefined
    at setEnvs (C:\npm-config-issue\node_modules\@npmcli\config\lib\set-envs.js:95:35)

Steps to Reproduce

// test.mjs
import Config from '@npmcli/config';
new Config({ types:{}, npmPath:'', defaults: {} }).load();

npm i @npmcli/config semver
node ./test.mjs

Expected Behavior

No error

References

// @npmcli/config/lib/set-envs.js:95
// is
  env.npm_execpath = require.main.filename
// should be 
  env.npm_execpath = require.main?.filename
// because require.main is empty when Node start with ESM main module

[isaacs]

Fixed on 40e9681