coverity#704673 Dereference after null check

Change-Id: I6302c2b8c721e7b2e2c640d905a0c95ee4ba711d

sc/source/core/data/funcdesc.cxx

@@ -321,7 +321,7 @@ void ScFuncDesc::fillVisibleArgumentMapping(::std::vector<sal_uInt16>& _rArgumen
         nArgs -= VAR_ARGS - 1;
     for (sal_uInt16 i=0; i < nArgs; ++i)
     {
-        if (!pDefArgFlags[i].bSuppress)
+        if (!pDefArgFlags || !pDefArgFlags[i].bSuppress)
             _rArguments.push_back(i);
     }
 }