🚀 Feature: Throw an error when the user has no packages on npm

[JoshuaKGoldberg]

Bug Report Checklist

• I have tried restarting my IDE and the issue persists.
• I have pulled the latest main branch of the repository.
• I have searched for related issues and found none that matched my issue.

Overview

Right now, if you run npx tidelift-me-up --username "#JI*#@%OJSL" (some username that definitely doesn't exist), it does ... nothing.

$ npx tidelift-me-up --username "#JI*#@%OJSL"
$ 

That could be confusing for folks who mistype their username. Let's have the package throw new Error when the user has no packages published to npm.

Additional Info

Right now, we fetch user npm packages with the npm-user-packages package here:

tidelift-me-up/src/tideliftMeUp.ts

Lines 24 to 26 in 148ddcb

	const userPackages = (await npmUserPackages(username)).filter(
	createUserPackagesFilter({ ownership, since: new Date(since), username })
	);