Notice: Undefined property: WP_User::$user_level in .../google-analytics-for-wordpress/googleanalytics.php on line 1444
This error(warning) is in function yoast_ga_do_tracking().
Code gets the use object:
$current_user = wp_get_current_user();
Then code looks for public property
Near as I can tell there is no such property.
There is a public method: get_role_caps() that looks like it is the proper way to handle looking for user abilities.
I can make the warnings go away. But I know no idea what the plugin would be doing if the proper method of checking abilities was used.