Domain Mapping Fatal Error -- Check for Upfront fails

Hello,

I have been working on a multi-user site with Domain Mapping and Upfront for the past several days. I have encountered a number of problems, but for the most part have been able to make do. When logging in recently, I was shown a PHP fatal error from the Domain Mapping plugin:

[Tue Oct 18 12:14:43.402213 2016] [php7:warn] [pid 1221] [client 127.0.0.1:54381] PHP Warning:  Parameter 1 to wp_default_styles() expected to be a reference, value given in /var/www/betterbetterbetter.website/public_html/wp-includes/plugin.php on line 600

[Tue Oct 18 12:14:43.503647 2016] [php7:error] [pid 1221] [client 127.0.0.1:54381] PHP Fatal error:  Uncaught Error: Call to a member function get() on boolean in /var/www/betterbetterbetter.website/public_html/wp-content/plugins/domain-mapping/classes/Domainmap/Module/Mapping.php:1117\nStack trace:\n#0 /var/www/betterbetterbetter.website/public_html/wp-content/plugins/domain-mapping/classes/Domainmap/Module/Mapping.php(295): Domainmap_Module_Mapping->redirect_upfront_to_mapped_domain()\n#1 /var/www/betterbetterbetter.website/public_html/wp-includes/plugin.php(524): Domainmap_Module_Mapping->redirect_front_area('')\n#2 /var/www/betterbetterbetter.website/public_html/wp-includes/template-loader.php(12): do_action('template_redire...')\n#3 /var/www/betterbetterbetter.website/public_html/wp-blog-header.php(19): require_once('/var/www/better...')\n#4 /var/www/betterbetterbetter.website/public_html/index.php(17): require('/var/www/better...')\n#5 {main}\n  thrown in /var/www/betterbetterbetter.website/public_html/wp-content/plugins/domain-mapping/classes/Domainmap/Module/Mapping.php on line 1117

This line reads as follows:

/**
	 * Decide if upfront should be redirected to mapped domain
	 *
	 * @since 4.4.2.0
	 * @return bool
	 */
	function redirect_upfront_to_mapped_domain(){

		if( class_exists("Upfront")  && "upfront" ===  strtolower( wp_get_theme()->parent()->get("Name") ) && isset( $_GET[ "editmode" ] ) )
			return "mapped" === $this->_get_current_mapping_type( 'map_admindomain' );
		else
			return true;
	}

Line 1117 begins with " if( class_exists("Upfront") ... ".

Domain mapping had to be disabled in order to access the Dashboard. (It's folder has a few x's after it now to rename it.)

Rather than chase the smoking stack trace into oblivion, it would be much nicer to have someone on your team who is familiar with this plugin. Let me know what you make of it.

Thanks,
Jeremy