                     if transitionStarted {
                         DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) {
                             guard let transitionContext = self.transitionContext else {
-                                fatalError("Invalid 'transitionContext' value. This property should not be nil")
+                                fatalError("Invalid transitionContext value. This property should not be nil")
                             }
                             if self.transitionStarted {
                                 self.cancelTransition(currentPercentComplete: progress)

        let totalWidth = screenWidth - options.visibleContentWidth

        guard let contentSnapshotView = self.contentSnapshotView else {
            fatalError("Invalid 'contentSnapshotView' value. This property should not be nil")
        }
        
        if present {

                
            case .changed:
                guard let transitionContext = transitionContext else {
                    fatalError("Invalid transitionContext value. This property should not be nil")
                }
                if transitionStarted && (present && dx > 0 || !present && dx < 0) {
                    updateTransition(percentComplete: progress)
