Those crash logs do nothing for me, but I know that we don't use that line of code in the latest version, so somehow the installation itself isn't working properly and it is leaving behind old files.
If you don't have a ton of other extensions installed I'd recommend renaming your Configuration folder which will essentially uninstall and remove all traces of old installations of all of your extensions at once. Then re-download and re-install all of the webassist extensions you are using from the site.
I'm confident that would resolve the issue.
Did this help? Tips are appreciated...
