anchor.diff:      kill_state(Vst);
   valfun_1({try_case_end,Src}, Vst) ->
       verify_y_init(Vst),
  -    assert_term(Src, Vst),
  +    assert_not_fragile(Src, Vst),
       kill_state(Vst);
   %% Instructions that cannot cause exceptions
   valfun_1({bs_get_tail,Ctx,Dst,Live}, Vst0) ->
  
positive.code: 	is_integer(Sz) ->
  	    ok;
  	true ->
  	    assert_term(Sz, Vst0)
      end,
      Vst1 = heap_alloc(Heap, Vst0),
      Vst2 = branch_state(Fail, Vst1),
  
negative.code:     St = St0#st{puts_left={Sz,{Dst,{tuple,Sz}}}},
      Vst#vst{current=St};
  valfun_1({put,Src}, Vst0) ->
      assert_not_fragile(Src, Vst0),
      Vst = eat_heap(1, Vst0),
      #vst{current=St0} = Vst,
      case St0 of
  