title: Setting a breakpoint on a running Emacs Lisp program
body: <p>I'm having a problem with an Emacs lisp package that I pulled down from the ubuntu distribution.  The package is JDEE, and it complains of <code>Args out of range: "63", 0, 4</code> in the mini buffer and the <code>*Messages*</code> buffer whenever I open a file.  This bug appears to have been reported last September but no action has been taken.  I'm not an emacs newbie, having written some Elisp code myself, but I've never attempted to debug anything like this.  I would like to stop the file load in a debugger when this error happens to at least get an idea of where the problem is coming from.  I've read section 18.1.1 of the Elisp manual on "Entering the debugger on error" but trying to load the file after playing with various combinations of values for <code>debug-on-error</code>, <code>debug-ignored-errors</code>, and <code>debug-on-signal</code> appears to have no effect.  Has anybody got any suggestions for my next step?</p>