I've looked into this several times and haven't really found an answer yet. Maybe I'm doing something wrong.
My main use case for the PHP APM agent (beyond monitoring performance) is to catch and alert if PHP raises a Warning or Error, or if it halts early due to an Uncaught exception. However in trying it out for several months on both a web server and a backend cli server I was never able to see it log a single one of these. It only seems to log the HTTP response code that the web server sends out.
Am I doing this wrong? I'm used to the NR APM where that's the main functionality of it and it alerts on those warning and errors out of the box. I personally am not interested in monitoring the HTTP response code.