np v8 breaking bug: NPM version check fails when npm is not specified in engines field in package.json

[JaneJeon]

Description

According to npm docs, it's okay to put engines.node but NOT engines.npm: https://docs.npmjs.com/cli/v9/configuring-npm/package-json?v=true#engines

However, np assumes that engines.npm IS specified, and so when you don't have engines.npm specified, it crashes with the message: "Please upgrade to npmundefined" (yes, that is verbatim)!

Steps to reproduce

Literally just run np in a repository with engines.node specified but not engines.npm specified in package.json

Expected behavior

For np to not throw when engines.npm is not specified.

From a quick glance, it looks like the issue is with this part:

np/source/version.js

Line 61 in c113539

const depRange = pkg.engines[dependency];

(where basicall you can't assume that the depRange is present).

Environment

np -8.0.0
Node.js - v18.16.0
npm - v9.5.1

[JaneJeon]

I can confirm that this error doesn't happen with np@7, meaning the issue is 100% from this PR: #683

So that should help narrow things down!

[JaneJeon]

I'll check the fix later, but thanks for the quick response :)