UndefinedBehaviorError.scala

trait Repository2 {
  type Input
  type Output
  val instance: Output

  private val scheme: String = dom.window.location.protocol
  private val host = dom.window.location.host
  protected val rootPath: Uri = Uri.unsafeFromString(s"$scheme//$host")
  protected val client: Client[IO] = FetchClientBuilder[IO].create
  protected val endPoint: String

  val event: PublishSubject[(Input, EventsDBWillDox)] = Subject.publish[(Input, EventsDBWillDox)]

  val onEvent: Observable[Either[Throwable, (Output, EventsDBResult)]]

  val onSuccess: Observable[Output] = onEvent.filter(_.fold(l => false, r => true))
                                        .map {
                                          case Left(value) => instance
                                          case Right((lst, event)) => lst
                                        }

}

trait Repository3 extends Repository2 {
    type Input = Recipe
    type Output = List[ItemRecipe]
    val instance: Output = List.empty[ItemRecipe]

    protected val endPoint = "getLstItemsRecipe"

    implicit val bodyPostEncode: EntityEncoder[IO, Input] = jsonEncoderOf
    implicit val responseDecode: EntityDecoder[IO, (Output, EventsDBResult)] = jsonOf

    override val onEvent: Observable[Either[Throwable, (Output, EventsDBResult)]] = {
     event.switchMap { bodyPost =>
          val (recipe, event) = bodyPost
          val bodyPostRefine = recipe
           Observable.fromEffect {
                client.fetchAs[(Output, EventsDBResult)](POST(bodyPostRefine, rootPath / endPoint))
                      .redeem (
                            error => (new Exception(error)).asLeft[(Output, EventsDBResult)],
                            something => something.asRight[Throwable]
                      )
                }
        }
     }
  }

  implicit val repoLstItemsRecipe3: Repository3 = new Repository3{}