When it comes to working with any type of development, especially WordPress development, I'm a fan of Spatie's Ray software.
It's significantly better than using var_dump or print_r to see what's going on in the system and it's not as heavy-handed or convoluted as a full debugger.
As such, I'm working on a comprehensive guide for how to use the software when building software for WordPress. Follow the series. If you enjoy it, please consider making a donation!