This totally ambiguous error is a pretty simple fix but surprisingly, not many people have said anything about it. The error comes from Firebug. The break on this error isn’t a part of the error but it is in the firebug copy dump.
syntax error [Break on this error] <!DOCTYPE html PUBLIC “-//W3C//DTD XHTML…3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”>
The way I encountered this error was that I forgot to specify a src attribute value for my script tag!
If your script tag has a strict xhtml doc type and you forget to specify a tag’s src value, it’ll yell at you.
The solution is that you must specifiy a value for all attributes.