Please keep debug mod turned off (we'll check this issue again in future releases).
But I think you're doing something wrong. This problem has been fixed and updated in wordpress.org repository. Do you have a copy of wpForo theme in wordpress theme folder? If so you should remove it too. The problem was in wpForo theme files and those should be deleted and isntalled again. After deleting wpForo you should download from wordpress.org for the new installation.
If you've made some changes in theme files you can only update /wpforo/wpf-themes/classic/footer.php file.
Actually I removed all the wpForo's files including the theme file, and I download from wordpress.org the wpForo and installed again, all settings became as default and the problem still there.
Ok, just keep the debug mode off. We'll check again and fix this issue in next release.