Adding a "View on website" -button to context menu in navigation tree in Episerver

Initializer.js

define([
    "dojo",
    "dojo/_base/declare",
    "epi-cms/plugin-area/navigation-tree",
    // Parent class
    "epi/_Module",
    // Commands
    "alloy/ViewOnWebsite/ViewOnWebsite"
], function (
    // Dojo
    dojo,
    declare,
    navigationTreePluginArea,
    // Parent class
    module,
    // Commands
    viewOnWebsite
) {

        return declare([module], {

            initialize: function () {
                this.inherited(arguments);
                navigationTreePluginArea.add(viewOnWebsite);
            }
        });
    });

module.config

<?xml version="1.0" encoding="utf-8"?>
<module>
  <assemblies>
    <!-- This adds the Alloy template assembly to the "default module" -->
    <add assembly="AlloyDemoKit" />
  </assemblies>
  <clientResources>
    <add name="epi-cms.widgets.base" path="Styles/Styles.css" resourceType="Style"/>
  </clientResources>
  <dojo>
    <!-- Add a mapping from alloy to ~/ClientResources/Scripts to the dojo loader configuration -->
    <paths>
      <add name="alloy" path="Scripts" />
    </paths>
  </dojo>
  <clientModule initializer="alloy.Initializer">
    <moduleDependencies>
      <add dependency="CMS" type="RunAfter" />
    </moduleDependencies>
  </clientModule>
</module>

ViewOnWebsite.js

define([
    "dojo/topic",
    "dojo/_base/declare",
    "epi/dependency",
    "epi/shell/command/_Command"
], function (topic, declare, dependency, command) {

    return declare([command], {

        label: "View on Website",
        iconClass: "epi-iconNewWindow",

        constructor: function () {
            var registry = dependency.resolve("epi.storeregistry");
            this.store = registry.get("epi.cms.contentdata");
        },

        _execute: function () {
            if (this.model != null && this.model.publicUrl != null) {
                var publicUrl = location.protocol + "//" + location.host + this.model.publicUrl;
                window.open(publicUrl, "_blank");
            }
        },

        _onModelChange: function () {

            this.set("canExecute", true);
        }
    });
});