title: EXC_BREAKPOINT when trying to present modally from storyboard in completion handler
body: <p>In my <code>ViewController.swift</code> I have this method which presents a viewcontroller modally after the animations for the boxes are completed: </p>
  
  <pre><code>@objc func sceneTapped(recognizer: UITapGestureRecognizer) {
      let location = recognizer.location(in: sceneView)
  
      let hitResults = sceneView.hitTest(location, options: nil)
  
      if hitResults.count &gt; 0 {
          let result = hitResults[0]
          let box = result.node
  
          let fadeAction = SCNAction.fadeOut(duration: 1.0)
          let rotateAction =  SCNAction.rotate(by: CGFloat(Double.pi*2), around: SCNVector3(x: 0.5, y: 1.5, z: 0), duration: 1.0)
          let groupActions = SCNAction.group([rotateAction, fadeAction])
  
          if box.name == Present.left.rawValue || box.name == Present.middle.rawValue || box.name == Present.right.rawValue {
              box.runAction(groupActions, completionHandler: presentWebView)
          }
  
      }
  
  }
  </code></pre>
  
  <p><code>presentWebView</code> uses the storyboard to instantiate the viewcontroller: </p>
  
  <pre><code>func presentWebView(){
          let storyboard = UIStoryboard(name: "Main", bundle: nil)
          let vc = storyboard.instantiateViewController(withIdentifier: "webViewController")
          self.present(vc, animated: true, completion: nil)
      }
  </code></pre>
  
  <p>But every time the app crashes on <code>self.present(vc, animated: true, completion: nil)</code> with <code>EXC_BREAKPOINT (code=1, subcode=0x1a1579b50)</code></p>
  
  <p>HOWEVER, when I don't present the view controller in the completion hander, i.e.:</p>
  
  <pre><code>@objc func sceneTapped(recognizer: UITapGestureRecognizer) {
      presentWebView()
  }
  </code></pre>
  
  <p>This works completely fine</p>
  
  <p>So I don't understand why presenting a view controller in a completion handler causes a crash. </p>
  
  <p>Any help would be greatly appreciated!</p>