Resolves: tdf#124927 crash on multiple drawing shapes in animation dialog

since...

SOSAW080: Added first bunch of basic changes to helpers
commit dfefe448
Date:   Thu Mar 1 15:54:32 2018 +0100

Change-Id: I9feba16b5efdbec5c817bebf2772e2f2882bdfe9
Reviewed-on: https://gerrit.libreoffice.org/72055Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>
Tested-by: Jenkins

sd/source/ui/tools/PreviewRenderer.cxx

@@ -199,13 +199,16 @@ bool PreviewRenderer::Initialize (
     const Size& rPixelSize,
     const bool bObeyHighContrastMode)
 {
-    if (pPage == nullptr)
+    if (!pPage)
         return false;
 
     SetupOutputSize(*pPage, rPixelSize);
     SdDrawDocument& rDocument(static_cast< SdDrawDocument& >(pPage->getSdrModelFromSdrPage()));
     DrawDocShell* pDocShell = rDocument.GetDocSh();
 
+    if (!pDocShell)
+        return false;
+
     // Create view
     ProvideView (pDocShell);
     if (mpView == nullptr)