title: Unable to use setTitle method when using a string concatenated with datastore data
body: <p>I have the following code attached as a handler to a button:</p>
  
  <pre><code>myapp.stores.vehicleInfo.load();
  myapp.toolbars.vehicleInfoToolbar.setTitle('Image 1 of ');
  </code></pre>
  
  <p>Which within my defined namespace loads the store and then sets the title of a toolbar - <strong>this works</strong>.</p>
  
  <p>This code doesn't work:</p>
  
  <pre><code>myapp.stores.vehicleInfo.load();
  myapp.toolbars.vehicleInfoToolbar.setTitle('Image 1 of' + myapp.stores.vehicleInfo.data.items[0].data.imageTotal);
  </code></pre>
  
  <p>giving the error: 'cannot read property of "data" of undefined'</p>
  
  <p>But when I click the button a second time, it sets the title of the toolbar as expected e.g. Image 1 of 10.</p>
  
  <p>What is going on here? How do I solve this? I tried using the settimeout method in case the setTitle method was being called too early before the store was finished loading. However this failed to solve the problem.</p>
  
  <p>Thanks.</p>