Domain Services and Notification Hexagon Edge

Are we forgetting something? the author should be notified by email, yeah! That's true. Let's see in Listing 16 how we have updated the UseCase for doing the job:

class RateIdeaUseCase
{
    private $ideaRepository;
    private $authorNotifier;

    public function __construct(
        IdeaRepository $ideaRepository,
        AuthorNotifier $authorNotifier
    ) {
        $this->ideaRepository = $ideaRepository;
        $this->authorNotifier = $authorNotifier;
    }

    public function execute(RateIdeaRequest $request)
    {
        $ideaId = $request->ideaId;
        $rating = $request->rating;

        try {
            $idea = $this->ideaRepository->find($ideaId);
        } catch(Exception $e) {
            throw new RepositoryNotAvailableException();
        }

        if (!$idea) {
            throw new IdeaDoesNotExistException();
        }

        try {
     ...