THREAD 1: signal SIGBART, when implementing camera function

Question

I'm having some trouble with implementing a camera function. I get signal SIGBART error in my @UIApplicationMain class AppDelegate: UIResponder, UIApplicationDelegate class, and I can't figure out why. I've tried searching in here, but without luck. Hopefully one of you can help!

@IBAction func cameraButtonAction(_ sender: Any) {
    if UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.camera){
        let imagePicker = UIImagePickerController()
        imagePicker.delegate = self
        imagePicker.sourceType = UIImagePickerControllerSourceType.camera;
    }