The ubuntu-desktop install packages for the Ubuntu desktop, it doesn't remove kubuntu if installed. That crash looks like another bug from the gtk2-engines-gtk-qt package which is something used by kubuntu to make GTK applications looking like KDE
The ubuntu-desktop install packages for the Ubuntu desktop, it doesn't remove kubuntu if installed. That crash looks like another bug from the gtk2-engines-gtk-qt package which is something used by kubuntu to make GTK applications looking like KDE