fix(cli): simplify empty event loop handling

[merceyz]

What's the problem this PR addresses?

The error added in https://github.com/yarnpkg/berry/pull/6399 should have used throw new Error() so that Node.js can handle the printing and provide a stack trace.

How did you fix it?

Use throw new Error() instead of printing an error ourselves.

Checklist

• [x] I have read the Contributing Guide.
• [x] I have set the packages that need to be released for my changes to be effective.
• [x] I will check that all automated PR checks pass before the PR gets reviewed.