tdf#160444 check device's owner window is a nullptr

Since commit 563f7077f1dbce31ff95ee8d2e8d17b629693db1, the
device's owner window gets deleted before this object is
deleted.

Change-Id: I15dc8db60e5520c2f0e73a9a117f25af15845caf
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/165637
Tested-by: Jenkins
Reviewed-by: Patrick Luby <guibomacdev@gmail.com>
diff --git a/svx/source/svdraw/svdpntv.cxx b/svx/source/svdraw/svdpntv.cxx
index 8653523..0958378 100644
--- a/svx/source/svdraw/svdpntv.cxx
+++ b/svx/source/svdraw/svdpntv.cxx
@@ -858,7 +858,12 @@ void SdrPaintView::InvalidateAllWin(const tools::Rectangle& rRect)
void SdrPaintView::InvalidateOneWin(OutputDevice& rDevice)
{
    // do not erase background, that causes flicker (!)
    rDevice.GetOwnerWindow()->Invalidate(InvalidateFlags::NoErase);
    // tdf#160444 check device's owner window is a nullptr
    // Since commit 563f7077f1dbce31ff95ee8d2e8d17b629693db1, the
    // device's owner window gets deleted before this object is
    // deleted.
    if (rDevice.GetOwnerWindow())
        rDevice.GetOwnerWindow()->Invalidate(InvalidateFlags::NoErase);
}

void SdrPaintView::InvalidateOneWin(OutputDevice& rDevice, const tools::Rectangle& rRect)