Wordpress plugin that utilizes Whoops! Error Page to show better PHP errors.
This may happen depending on where the error occurred. Because this is set up as a WordPress plugin, if for some reason a PHP error happens before this plugin is able to load, the pretty PHP error page will not be displayed. Also make sure that WP_DEBUG is set to true, or this plugin will do nothing.
You will need to install [Whoops!]http://filp.github.io/whoops/ manually. I would suggest setting it up in your wp-config.php file, so that it is loaded and ready to go before WordPress really get's loaded.