tdf#120703 PVS: nullptr dereference

V595 The 'pContact' pointer was utilized before it was verified against nullptr.
     Check lines: 1254, 1256.

Change-Id: I5d3d28b3c8a70924f329fde9f020f42d9eb5e9a1
Reviewed-on: https://gerrit.libreoffice.org/71459
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

sw/source/core/doc/doclay.cxx

@@ -1253,10 +1253,10 @@ SwFlyFrameFormat* SwDoc::InsertDrawLabel(
 {
     SwDrawContact *const pContact =
         static_cast<SwDrawContact*>(GetUserCall( &rSdrObj ));
-    OSL_ENSURE( RES_DRAWFRMFMT == pContact->GetFormat()->Which(),
-            "InsertDrawLabel(): not a DrawFrameFormat" );
     if (!pContact)
         return nullptr;
+    OSL_ENSURE( RES_DRAWFRMFMT == pContact->GetFormat()->Which(),
+            "InsertDrawLabel(): not a DrawFrameFormat" );
 
     SwDrawFrameFormat* pOldFormat = static_cast<SwDrawFrameFormat *>(pContact->GetFormat());
     if (!pOldFormat)