Where do PHP errors get logged in a private custom app?

[MastaP]

Hi! - first post. 😉

I am building a PHP private Shopify custom app for a store.

If a PHP code returns an error (warning, notice, parse or fatal Error) while running on production, where is this logged?

I would like to ensure that I can go through a certain journal to review all the errors generated by my app in the last 5 days. Just like Apache would do on a regular PHP script. to error_log

Please clarify. Thanks!