[core] fixing clang-tidy in Match.cxx [#7412]
[core] fixing clang-tidy in Match.cxx [#7412]

core/base/src/Match.cxx:383:19:
core/base/src/Match.cxx:391:51:
warning: Dereference of null pointer
clang-analyzer-core.NullDereference]

olifre/root,root-mirror/root,olifre/root,root-mirror/root,root-mirror/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root,root-mirror/root,olifre/root