When I Tap the imageView, App crashed

[kitanai-kitsune]

import UIKit import ImageViewer

class ViewController: UIViewController, GalleryItemsDataSource {

var galleryItem: GalleryItem!

override func viewDidLoad() {
    super.viewDidLoad()

    let image = UIImage(named: "sample")
    galleryItem = GalleryItem.image{ $0(image) }

    let imageView = UIImageView(frame: CGRect(x: 100, y: 100, width: view.frame.width - 100*2, height: 200))
    imageView.image = image
    imageView.contentMode = UIImageView.ContentMode.scaleAspectFill
    view.addSubview(imageView)

    imageView.isUserInteractionEnabled = true
    let recognizer = UITapGestureRecognizer(target: self, action: #selector(self.onTap(_:)))
    imageView.addGestureRecognizer(recognizer)
}
@objc func onTap(_ sender: UIImageView) {
    let galleryViewController = GalleryViewController(startIndex: 0, itemsDataSource: self, configuration: [.deleteButtonMode(.none), .seeAllCloseButtonMode(.none), .thumbnailsButtonMode(.none)])
    self.present(galleryViewController, animated: true, completion: nil)
}

// MARK: GalleryItemsDataSource
func itemCount() -> Int {
return 1
}

func provideGalleryItem(_ index: Int) -> GalleryItem {
return galleryItem
}

}

[IhorKram]

I have the same problem. Could you tell me, how you deal with it?