Installing non-existent npm packages causes general "Failed to fetch" error due to missing CORS in the npm registry

[naruaway]

Trying to install non-existent npm package such as this-pkg-does-not-exist-6820863782039188 causes Failed to fetch error, which cannot be distinguished from real network error.

This is because registry.npmjs.org does not return Access-Control-Allow-Origin: * for "HTTP 404 Not Found" responses.

See https://github.com/naruaway-sandbox/demo-npm-in-browser-not-found-cors for more details and reproduction steps.

I reported in npm/feedback#117 (comment) as well.

Actual

npm ERR! Failed to fetch

npm ERR! A complete log of this run can be found in: /home/web/.npm/_logs/2023-09-28T05_07_54_094Z-debug-0.log

Expected (the same as npm CLI in local machine)

npm ERR! code E404
npm ERR! 404 Not Found - GET http://localhost:8745/this-pkg-does-not-exist-6820863782039188 - Not found
npm ERR! 404
npm ERR! 404  'this-pkg-does-not-exist-6820863782039188@*' is not in this registry.
npm ERR! 404
npm ERR! 404 Note that you can also install from a
npm ERR! 404 tarball, folder, http url, or git url.

npm ERR! A complete log of this run can be found in: /home/web/.npm/_logs/2023-09-28T05_07_19_717Z-debug-0.log