Enforce committing yarn.lock when changing dependencies

This executable is meant to be executed as a git pre-commit hook for npm projects using yarn.

Whenever changes are made to one of package.json's dependency properties, if no change is staged in yarn.lock as well, this program emits an error message.

$3

To use a commit hook, add an execution check-yarn-lock to your repository's pre-commit hook.
This can be made easier using husky.