Option to output PHP errors

[nick-vanpraet]

I noticed that if a PHP error occurs (e.g. someone uses a formatterType that does not return a string but an object) the process exits with an error code (PHP Fatal Error) but, as far as I could find, the actual error is not logged anywhere.

It'd be nice if either the existing debug option also output any PHP errors, or perhaps it already gets logged somewhere and I just missed it.