message: bug-fix in BuildConformingProlongation
diff: @@ -1055,6 +1055,7 @@ void FiniteElementSpace::BuildConformingInterpolation() const
  // get lowest order variant DOFs and FE
  int p = GetEntityDofs(entity, i, master_dofs, geom, 0);
  const auto *master_fe = fec->GetFE(geom, p);
  + if (!master_fe) { break; }
  // constrain all higher order DOFs: interpolate lowest order function
  for (int variant = 1; ; variant++)
  