How to debug ajax requests?

Hi! New CI user here. Pretty happy with it so far, but the things that puzzles me is debugging failed ajax requests.

So far I've been able to figure out what is going on by manually adding breakpoints, but I'd like to just get the regular error feedback CI normally provides when I visit the page directly, instead of receiving a blank 500 (Internal Server Error).

Am I missing something here?

How about using Network tab?