title: PromiseKit AnyPromise then crash EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x0000000000000010
body: <p>I have a crash in Fabric that points to the first line in Objective-C:</p>
  
  <pre><code>somePromise.then(^ {
    // some more code
  });
  </code></pre>
  
  <p>The app is using PromiseKit. Why is this crashing?</p>