NodeInstantiator doesn't reflect model changes

If the NodeInstantiator is used with an (Abstract-)ListModel, it doesn't reakt to changes of the number of ListElements (although the count property is updated correctly). Furthermore if the number of ListElements is reduced, the program crashes.

Attached you will find a simple example which demonstrates the behaviour. A QtQuick Timer is used to add elements to a ListModel every second. This ListModel is used with a NodeInstantiator to display a variable number of spheres. When the model count reaches 10, all ListElements are cleared from the ListModel.

While this Program should display an increasing number of spheres (up to 10) only the initial two spheres are displayed (and moved according to the count property). After the ListModel has been cleared, the program crashes.