title: iOS9 Storyboard "Setting empty vector for variable" exception - Terminating app due to uncaught exception 'NSInternalInconsistencyException'
body: <p>I'm running into an issue where my main storyboard got corrupted after I messed around with it, and I get the following cryptic error message. The app catches error in <code>main()</code> and is followed by <code>SIGABRT</code> with the following exception:</p>
  
  <pre><code>  Terminating app due to uncaught exception 'NSInternalInconsistencyException', 
  reason: '{objective 0x147dc56e0: &lt;1:-25.3333&gt; + &lt;1:1&gt;*0x147dc39b0.posErrorMarker{id: 91} +
   &lt;1:0.125&gt;*0x147dc50e0.negError{id: 90} +
   &lt;1:-0.125&gt;*0x147e2e300.marker{id: 77} +
   &lt;1:0.125&gt;*0x147e2e300.slack{id: 78} +
   &lt;1:0.125&gt;*0x147e2e350.marker{id: 81} +
   &lt;1:-1&gt;*0x147e2e440.marker{id: 87} +
   &lt;1:-0.125&gt;*0x147e436b0.marker{id: 63} +
   &lt;1:0.125&gt;*0x147e437f0.marker{id: 72} +
   &lt;1:-0.125&gt;*0x147e764c0.marker{id: 55} +
   &lt;1:0.125&gt;*0x147e88820.marker{id: 52}}:
   internal error.  Setting empty vector for variable 0x147dc1b90.negError{id: 48}.'
  </code></pre>
  
  <p>Setting another storyboard to be the main interface has the app starting up correctly. </p>
  
  <p><strong>How can I find the element that is causing "Setting empty vector for variable" storyboard exception?</strong></p>