QSortFilterProxyModel: cannot remove items from proxy-to-source mapping

I'm currently using my own QAbstractItemModel and QSortFilterProxyModel.

When I try to delete an item out of my treeview, the whole thing crahes. But only with the lowest items in the treeview:

XX

 | ------ XX
 
            |------ YY

YY = crash when deleting

Callstack:

The error occurs, when calling the beginRemoveRows method of QAbstractItemModel.

After calling q->beginRemoveRows(.......) in remove_proxy_interval, the proxy_to_source vector doesn't work anymore.

If you need any more infos, just ask.