Trivial Description
I was getting messages in my debug console the simply read
ERROR: [Object error]
While at least I knew there was a problem, I had no idea what was causing it or where to look. What was helpful to me was modifying wicket-ajax.js to include a little more information with the error message. At the least, it names the wicket-ajax function that threw the error which jumpstarts the debugging process. For those errors thrown in the catch around an eval() method, I also include the text being eval'ed.
So, my recommendation is to include this extra text in the error messages to speed debugging of ajax javascript errors