Comment 1 for bug 1433056

I can't prove that the attached branch really fixes the backtrace of this bug but this crash is caused because on line

const bool firstItemWithViewOnTop = insert.index == 0 && m_firstVisibleIndex == 0 && m_visibleItems.first()->y() + m_clipItem->y() > contentY();

insert.index is 0 and m_firstVisibleIndex is 0 but m_visibleItems.first()->y() crashes (i.e. it's probably empty) and this fixes a case in which m_firstVisibleIndex may get out of sync so I'd say let's merge this fix and let's monitor errors.ubuntu.com to see if it continues or it is indeed fixed by this.