The face NoTopologyType for Tetrahedron_10 was set to both NoTopologyType and Triangle_6. It make no sense to define the face topology with two different types, NoTopologyType is probably a left over from a copy paste, and so this MR remove this line.
@ben.boeckel you have already merged the same commit here xdmf/xdmf!57 (merged) but I would like to get it ported into vtk. So please let me know if this is not the correct way to get it into vtk.