Plugin Crashing site

Hi there,

First time installing this plugin. I seem to be getting an error that crashes the site. Maybe it is plugin conflict or maybe it relates to the latest update.

Getting this error in logs:

mod_fcgid: stderr: PHP Fatal error: Call to undefined function is_user_logged_in() in /var/www/vhosts/some/site/wp-content/plugins/accesspress-anonymous-post/accesspress-anonymous-post.php on line 370, referer: http://www.somesite.com/wp-admin/plugin-install.php?s=anonymous+post&tab=search&type=term

any pointers much appreciated!