In Erlang, B will log only what stack accumulated in B's process. Nothing from A's. That is -

  run() ->
    B = spawn(fun() -> receive_func() end),
    A = spawn(fun() -> send_func(B), io:format("A completed normally", []) end).

  send_func(Pid) -> Pid ! whatever.

  receive_func() -> receive _ -> throw(blah) end.

You will receive a call stack listing only an error in receive_func. You will not have the anonymous function in B (due to tail call optimization) in the call stack, and you will not have the send_func in the call stack, at all, because that process completed normally; there was no error involved with it (a fact you can see by the io format call, which will be invoked just fine). A sent its message, and then printed something, and that's it. B's error does not relate to A; A might have a separate error (such as if I were to add a receive clause to send_func, expecting a response, that times out after a while), but that error is unrelated to B, and will create an entirely separate error in the logs, with an entirely separate call stack.