First, thanks for this great and useful plugin!
After installing the Better WP Security plugin I was recommended to remove the User with ID one and did so. Then the Tree View plugin crasched. - but only when WP_Debug was true.
Apparently WP throws and error in the author-template.php file, and my best guess is that it's trying to get info from the first user who now doesn't exist anymore.
(Trying to get property of non-object)
So, disabling debug solves it.
Adding a check in author-template.php if the user is returned also solves the problem but I'd rather not edit code in the WP-core.
Is it possible that this plugin can take care of this issue?