coverity#1437956 Dereference after null check

Change-Id: Idcfb63beb094a000c70f594542757ad2e4a577fc
Reviewed-on: https://gerrit.libreoffice.org/57459Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

sd/source/ui/view/outlnvsh.cxx

@@ -1598,6 +1598,7 @@ void OutlineViewShell::UpdateTitleObject( SdPage* pPage, Paragraph const * pPara
         if (pOPO)
         {
             pOPO->SetOutlinerMode( OutlinerMode::TitleObject );
+            assert(pTO);
             pOPO->SetVertical( pTO->IsVerticalWriting() );
             if( pTO->GetOutlinerParaObject() && (pOPO->GetTextObject() == pTO->GetOutlinerParaObject()->GetTextObject()) )
             {