[ntuple] Prevent current reading code from choking on 0-byte clusters
[ntuple] Prevent current reading code from choking on 0-byte clusters

olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root