title: App aborts when data type of entity changed
body: <p>I have created an entity in my core data and mistakenly kept the type as <code>String</code> instead of <code>Boolean</code>. When I attempt to change the type to <code>Boolean</code>, the app aborts with no exception during the save.</p>
  
  <p>I tried cleaning the app, deleting the folders of simulators, and none worked.</p>
  
  <p>Why is my app aborting after the change?</p>