SwipeView: dynamic creation / deletion of subpages crashes application

I'm trying to dynamically create / delete subpages of a SwipeView using a Repeater. If I assign a arbitrary but fixed int value to the repeater model, everything works fine. As soon as I try to change this value during runtime the application crashes. In the attached code you can either click twice on the decrease or the increase button or click on one of the buttons and do a swipe. Using the same repeater in the same way in a Row (see attached code line 32ff) works as expected.