Xcode 8 - Found nil while unwrapping an Optional value - cannot find the crashing line
<blockquote>
  <p>fatal error: unexpectedly found nil while unwrapping an Optional value</p>
</blockquote>

<p>I cannot see the crashing line because of the last "message from debugger":</p>

<blockquote>
  <p>Message from debugger: The LLDB RPC server has crashed. Please file a
  bug with Apple with the crash log.</p>
</blockquote>

<p>It just crashes and I can't debug my app. I've tried putting some "debug prints" in the code but it is just impossible to find the bug.</p>

<p>BTW, I use the same code as I used before Swift 3, and this nil error wasn't there.</p>

<p>If it helps, I use FBSDK and Alamofire.</p>