filter for plugins that have defined properties

lib/core/plugins.js

@@ -111,6 +111,8 @@ Plugins.prototype.getPluginsProperty = function(pluginType, property, sub_proper
     return plugin[property];
   });
 
+  matchingProperties = matchingProperties.filter((property) => property);
+
   //return flattened list
   if (matchingProperties.length === 0) return [];
   return matchingProperties.reduce((a,b) => { return a.concat(b); }) || [];