coverity#704873 Unchecked dynamic_cast

Change-Id: I03580779ba69a71e51e9e4e1349fe2f5d77956d5

sw/source/core/doc/doctxm.cxx

@@ -417,6 +417,7 @@ const SwTOXBaseSection* SwDoc::InsertTableOf( sal_uLong nSttNd, sal_uLong nEndNd
 
     SwTOXBaseSection *const pNewSection(
         dynamic_cast<SwTOXBaseSection*>(& pNewSectionNode->GetSection()));
+    if (pNewSection)
         pNewSection->SetTOXName(sSectNm); // rTOX may have had no name...
     return pNewSection;
 }