I've recently updated from actions/checkout@v5 to actions/checkout@v6, and that update breaks this action.
We now get an error saying fatal: could not read Username for 'https://github.com': No such device or address when it tires to call cr index.
It may be helpful to add some info to the README here saying how to configure actions/checkout@v6 to work with this action.
Reverting the checkout action back to v5 caused this to work again, so it's just some kind of incompatibility between these actions.