This is a serious problem, though it doesn't happen to me, so not sure how to proceed.
The next line in the log should have been:

Generated {<P>Onclose <A href='javascript:document.body.onunload()'>Body</A><br><P>Onclose <A href='javascript:document.forms[0].onunload()'>Form</A><br></body>

somewhere between finishing the selector audit in rebuildSelectors()
and managing the document.write string, something goes wrong,
or perhaps went wrong earlier and is detected at this point.

Karl Dahlke