title: Sencha Touch 2 Store TypeError
body: <p>I'm following the video on the Sencha website, for creating my first application.</p>
  
  <p>This is the video I'm following: <a href="http://player.vimeo.com/video/37974749" rel="nofollow" title="Video">Video</a></p>
  
  <p>This is the code I'm using for the Blog tab:</p>
  
  <pre><code>Ext.define('GS.view.Blog',{
      extend: 'Ext.navigation.View',
      xtype: 'blogpanel',
  
      requires: [
          'Ext.dataview.List',
          'Ext.data.proxy.JsonP'
      ],
  
      config: {
          title: 'Blog',
          iconCls: 'star',
  
          items: {
              xtype: 'list',
              itemTpl: '{title}',
  
              store: {
                  autoLoad: true,
                  fields: ['title', 'author', 'content'],
  
                  root: {
                      leaf: false
                  },
  
                  proxy: {
                      type: 'jsonp',
                      url: 'https://ajax.googleapis.com/ajax/services/feed/load?v=1.0&amp;q=http://feeds.feedburner.com/SenchaBlog',
  
                      reader: {
                          type: 'json',
                          rootProperty: 'responseData.feed.entries'
                      }
                  }
              }
          }
      }
  });
  </code></pre>
  
  <p>In the Safari Console, it is giving me the following error on StoreManager.js:97:</p>
  
  <pre><code>TypeError: 'undefined' is not a valid argument for 'instanceof' (evaluating 'store instanceof Ext.data.Store')
  </code></pre>
  
  <p>What am I doing wrong?</p>