[clingutils] prevent usage of nullptr in ReSubstTemplateArg #7423
[clingutils] prevent usage of nullptr in ReSubstTemplateArg #7423
root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root,olifre/root,root-mirror/root,olifre/root,root-mirror/root,olifre/root,olifre/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,olifre/root,olifre/root,root-mirror/root,olifre/root