private void failLateProcessorSubscriber0() {
            try {
                subscriber.onSubscribe(NoopSubscription.get());
                subscriber.onError(
                        new IllegalStateException("duplicator is closed or no more downstream can be added."));
            } catch (Throwable t) {
                throwIfFatal(t);
                logger.warn("Subscriber should not throw an exception. subscriber: {}", subscriber, t);
            }
        }
{@link CancelledSubscriptionException} if cancelled. {@link Throwable} if aborted.
core/src/main/java/com/linecorp/armeria/common/stream/DefaultStreamMessageDuplicator.java