Course Press Pro activation crashes WP site

Hi there,

No problem installing the plugin through the WPMU Dev Dashboard but when we activate the plugin (through the dashboard or through the regular WP plugins page) our whole WP site goes offline. I enabled WP_Debug and returned the fatal error below

Fatal error: Can't use function return value in write context in /opt/bitnami/apps/wordpress/htdocs/wp-content/plugins/coursepress/2.0/include/coursepress/data/shortcode/class-coursetemplate.php on line 425

Line 425 appears to be "if ( empty( wp_script_is( 'coursepress-front-js' ) ) ) {"

Renaming the plugin directory brings our site back online and deactivates the plugin but we would like to use the plugin still and have our website online. Thoughts?