Renamed js to ignite-html-tabs. Added null check on element.

ignite-html-tabs.js

@@ -14,6 +14,7 @@ IgniteTemplate.prototype.tab = function(name, active = false) {
     //the tabchange event is raised. Upon disconnecting the callback we remove
     //the event listener.
     var callback = new IgniteCallback(e => {
+        if (this.element) {
             if (e.tabName == name) {
                 this.element.classList.remove("tab-inactive");
 
@@ -27,6 +28,7 @@ IgniteTemplate.prototype.tab = function(name, active = false) {
                     this.element.classList.add("tab-inactive");
                 }
             }
+        }
     }, () => {
         window.removeEventListener("tabchange", callback.callback);
     });