fix bug 1044093 - friendlier kumascript errors

**DNM** yet ... still have a couple TODOs.
@groovecoder hehe, I'm really not sure how AT would handle that, but the [spec](http://www.w3.org/html/wg/drafts/html/master/text-level-semantics.html#the-a-element) says that the content model is `Transparent, but there must be no interactive content descendant.` In other words, it's not valid. Mostly because the browser doesn't know what to do, follow the click-event on the button or the link :)