message: PetscSolver::SetPreconditionerFactory : prevent from segfaulting
diff: @@ -1976,8 +1976,15 @@ void PetscSolver::SetPreconditionerFactory(PetscPreconditionerFactory *factory)
  {
  MFEM_ABORT("No support for PetscPreconditionerFactory for this object");
  }
  + if (factory)
  + {
  ierr = MakeShellPCWithFactory(pc,factory); PCHKERRQ(pc,ierr);
  }
  + else
  + {
  + ierr = PCSetType(pc, PCNONE); PCHKERRQ(pc,ierr);
  + }
  +}
  void PetscSolver::Customize(bool customize) const
  {
  