Recently hoek 6.1.0 was unpublished from npm. My team had already upgraded and locked to that version. When it was unpublished, npm install would return the following error:
npm ERR! code E404 npm ERR! 404 Not Found: firstname.lastname@example.org
Better would be to have npm report something like this
npm ERR! <package>@<bad version> was unpublished from <repository url> on <date> with message <unpublish message>
That would create a great deal more clarity on what was actually happening.