having some issues with the webdesktop example.

I am trying to link my independent running page within the webdesktop example and getting an error.
Error is
Code:
TypeError: c is null
My window create and load code is
Code:
createWindow : function(ttl,src){        var desktop = this.app.getDesktop();
        var win = desktop.getWindow('bogus'+src.windowId);
        if(!win){
            win = desktop.createWindow({
                id: 'bogus'+src.windowId,
                title:ttl,
                width:640,
                height:480,
                //html : '<p>Something useful would be in here.</p>',
                iconCls: 'bogus',
                animCollapse:false,
                //autoLoad: src,
                loader : {
                    url : '/modules/app.html',
                    loadMask : true,
                    scripts: true,
                    autoLoad : true, // important
                    renderer : 'html', // this is also the default option, other options are data | component
                    success: function(el,response,opts) {
                        //your logic here
                    },
                    failure:function(el,response,opts) {
                        // your logical statements here
                    }
                },
                constrainHeader:true
            });
        }
        win.show();
        return win;
    }
and my app.html file only loads app.js which is
Code:
/* * File: app.js
 *
 * This file was generated by Sencha Architect version 2.1.0.
 * http://www.sencha.com/products/architect/
 *
 * This file requires use of the Ext JS 4.1.x library, under independent license.
 * License of Sencha Architect does not include license for Ext JS 4.1.x. For more
 * details see http://www.sencha.com/license or contact license@sencha.com.
 *
 * This file will be auto-generated each and everytime you save your project.
 *
 * Do NOT hand edit this file.
 */


Ext.Loader.setConfig({
    enabled: true
});


Ext.application({
    models: [
        'Model_Parts'
    ],
    stores: [
        'MyJsonStore'
    ],
    views: [
        'GridPanel'
    ],
    autoCreateViewport: true,
    name: 'MyApp'
});