There are quite some tutorials out there on how to use XDebug to debug PHP CLI code, which where more confusing than helpful (to me). I found out that, once you have a running XDebug configuration, it is very easy to debug on the console, particularly with phpStorm.
Simply run the following line once
export PHP_IDE_CONFIG=serverName=www.domain.com ; export XDEBUG_CONFIG=idekey=PHPSTORM
(after customizing it to your needs, of course), set your breakpoints and run the script. That’s already it. You can also put this into your .bashrc file.