Validate packages before publishing them

[redbar0n]

Request for NPM to validate packages before publish.

Especially for ESM, since: Node.js is chocking on npm packages having invalid ESM.

The validation doesn't have to cover everything. Only validating basics things like the following would make a big impact already:

a widespread problem is npm packages having invalid ESM imports, e.g. import './foo' instead of import './foo.js', which makes Node.js choke. Another example is packages that ship ESM but don't have type: "module" in their package.json. Node.js should be able to execute npm packages that ship invalid code.

npm/rfcs#665 (comment)

But also for CJS:

You can write invalid CJS packages as well. And we see that happen constantly. E.g. "type": "module" and CJS code with .js extension - the CJS code won't run on Node. Node packaging has gotten more complicated since the introduction of exports, .cjs/.mjs, etc. and we see packages published to npm that won't run on Node on a non-stop basis.

npm/rfcs#665 (comment)

See @brillout's original request, for details and initial discussion: npm/rfcs#665

Reposting it here due to notice that this might be the more appropriate place.