feat: add npm user validity check

[maggienegm]

PR Checklist

• Addresses an existing open issue: fixes 🚀 Feature: add npm user validity check #649
• That issue was marked as status: accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

This PR adds a user validity check if the API response from the npm registry API returns zero packages to differentiate between invalid npm users and valid users with zero packages.

How It Works

1. The npm registry API is queried with the npm username input.
2. If the response contains one or more packages, result is returned as usual. (This is the "happy" case.)
3. If the response contains 0 packages, check if npm username exists using the npm-user wrapper.
4. If npm username doesn't exist, return an Invalid npm username. error.
5. If npm username does exist but user has zero packages, return a No packages found for npm username: ${username}. error.

Testing

I updated the unit tests that were affected by these changes and then I ran the unit tests using pnpm run test.

🤖

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.39%. Comparing base (27c442d) to head (479e74a).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #659      +/-   ##
==========================================
+ Coverage   99.35%   99.39%   +0.03%     
==========================================
  Files          25       25              
  Lines         778      824      +46     
  Branches      122      127       +5     
==========================================
+ Hits          773      819      +46     
  Misses          5        5              

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[JoshuaKGoldberg]

A good start! I think the core idea is solid. Requesting a bit of touching up on the error, a refactor for clarity, and some testing.

[maggienegm]

Looks like the checks are failing due to a ERR_PNPM_BROKEN_LOCKFILE error.

[JoshuaKGoldberg]

Weird, looks like it was some kind of merge weirdness from #669. I fixed it on main.

[maggienegm]

Thank you! I updated this branch with main, and during the merge process, the version number of one of the dependencies didn't update for some reason (it didn't show in the merge conflicts?). But I fixed it and now this PR should be good to go!

[JoshuaKGoldberg]

Looking great, just one more refactor to talk about!

[JoshuaKGoldberg]

This is probably the first time I've seen throw await actually used 😄 very nice! 🔥