CFTREE Variable DEBUGGER is undefined. help!

I get this error working Coldfusion ajax tag CFTREE, i have googled around and looked thru the CF docs but I couldn't find the answer... anyone?

Does anyone have a working example of the error handler?

update:1 this url parameter causes it... "_cf_nodebug=true"

I also had cfdebug set as a url parameter on the calling page

update 2: I was looking at CFTREE and not the tag I was binding with which is
cftreeitem that has a onBindError parameter.

I can now nicely display "500 Variable DEBUGGER is undefined"...