private static void failLateSubscriber(EventExecutor executor,
                                               Subscriber<?> lateSubscriber, Subscriber<?> oldSubscriber) {
            final Throwable cause = abortedOrLate(oldSubscriber);

            executor.execute(() -> {
                try {
                    lateSubscriber.onSubscribe(NoopSubscription.get());
                    lateSubscriber.onError(cause);
                } catch (Throwable t) {
                    throwIfFatal(t);
                    logger.warn("Subscriber should not throw an exception. subscriber: {}", lateSubscriber, t);
                }
            });
        }
Returns the default {@link EventExecutor} which will be used when a user subscribes to a child
stream using {@link StreamMessage#subscribe(Subscriber, SubscriptionOption...)}.
core/src/main/java/com/linecorp/armeria/common/stream/DefaultStreamMessageDuplicator.java