QA/QA-searchcrawllog.jsp does not tell, if the search went wrong

The functionality Display all crawl.log lines matching this regexp using
JSP page /QA/QA-searchcrawllog.jsp does not distinguish between returning zero lines
because there is no match or because the regular expression is malformed.

Furthermore there is no logging of the problem in the bitarchive-logs.
We hear of the fact that the processing failed for a file