coverity#735842 Explicit null dereferenced

Change-Id: I53112795f301679429afb8da4e01c77e4d2fe820

sd/source/ui/unoidl/unomodel.cxx

@@ -1871,7 +1871,7 @@ void SAL_CALL SdXImpressDocument::render( sal_Int32 nRenderer, const uno::Any& r
                 vcl::PDFExtOutDevData* pPDFExtOutDevData = PTR_CAST( vcl::PDFExtOutDevData, pOut->GetExtOutDevData() );
 
                 if ( !( (mpDoc->GetSdPage((sal_Int16) nPageNumber-1, PK_STANDARD))->IsExcluded() ) ||
-                    pPDFExtOutDevData->GetIsExportHiddenSlides() )
+                    (pPDFExtOutDevData && pPDFExtOutDevData->GetIsExportHiddenSlides()) )
                 {
                     ::sd::ClientView* pView = new ::sd::ClientView( mpDocShell, pOut, NULL );
                     Rectangle               aVisArea = Rectangle( Point(), mpDoc->GetSdPage( (sal_uInt16)nPageNumber - 1, ePageKind )->GetSize() );