QQuickRepeater::setModel calls ::clear which iterates all items from 0 to size and emites 'removed' signal for all of them.
The problem is that if we have 3 items the order of signals is the following:
1. removed(0);
2. removed(1);
3. removed(2); // Oops, size is 1 and we already don't have item at index 1

Looks like items have to be iterated in reverse order or removed signal argument should be fixed accordingly to current number of elements.