I agree with DHalo.
The error message is being generated by your browser. (Are you using Firefox?)
The line in the source looks like it is supposed to be a remark. IE gives more detail on this error.
I don't really understand XML all that much, so I don't know what the problem is. I think it's complaining about the extra - on the right side.
However, being that this isn't something public users are supposed to be looking at, I believe we can safely assume this will not produce any ARG information.