anchor.diff:  
   -spec bp_step(pid()) -> {module(), On::atom(), comm:message()}.
   bp_step(Pid) ->
  -    ?TRACE_BP_STEPS("Do step ~p ~p~n", [Pid, pid_groups:group_and_name_of(Pid)]),
  +    ?TRACE_BP_STEPS("Do step ~p ~p~n", [Pid, catch pid_groups:group_and_name_of(Pid)]),
       Pid !  {'$gen_component', bp, breakpoint, step, self()},
       receive {'$gen_component', bp, breakpoint, step_done,
                _GCPid, Module, On, Msg} ->
  
positive.code:                             "    Process: ~p (~p)~n"
                              "    Handler: ~p:~p/2~n"
                              "    Message: ~.0p~n",
                              [self(), pid_groups:group_and_name_of(self()),
                               gc_mod(State), gc_hand(State), Msg]),
              self() ! {'$gen_component', bp, breakpoint, step,
                        gc_bpstepper(State)},
  
negative.code:             [UnknownMessage,
               gc_mod(State),
               gc_hand(State),
               self(), catch pid_groups:group_and_name_of(self()),
               State]),
      State.
  
  