How to get firebug to break on exception?

Question

I\'m using Firebug 1.5.4. When I reference an undefined variable or some such, it breaks right where the problem occurs, and throws me into the debug view where I can see t

Answer 1

Call Web Developer Debugger (Tools => Web Developer => Debugger or Ctrl + Shift + S), click gear icon and check "Pause on exception":

Or execute debugger; in Web Developer Console!

Official Web Developer Debugger docs: https://developer.mozilla.org/en-US/docs/Tools/Debugger