title: UICollectionView Assertion failure in deleteItemsAtIndexPaths
body: <p>Here is my error:</p>
  
  <pre><code>*** Assertion failure in -[PSUICollectionView _endItemAnimations], /SourceCache/UIKit_Sim/UIKit-2372/UICollectionView.m:2801
  </code></pre>
  
  <p>I'm calling it like this:</p>
  
  <pre><code>[self.collectionView deleteItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:1 inSection:1]]];
  </code></pre>
  
  <p>Why is this happening, any ideas?</p>