Fix for https://en.wikipedia.org/wiki/Wikipedia_talk:AutoWikiBrowser/Bugs#ArgumentException_in_DatabaseScanner.btnBrowse_Click

git-svn-id: svn://svn.code.sf.net/p/autowikibrowser/code/AWB@9340 5227b50d-9349-4574-b055-4b0a7525e11c