阿克卡监管违约行为

我正在努力学习阿卡监督战略。当我有下面这样的代码时,我会得到这个

java.lang.arithmeticException:/by零

case object CreateChildren
case class DivideNumbers(n: Int , d:Int)
object SuperVision extends App {
  val actorSystem = ActorSystem("SupervisingActorSystem")
  val actor = actorSystem.actorOf(Props[ParentActor], "ParentActor")
  actor ! CreateChildren
  val child1 = actorSystem.actorSelection("/user/ParentActor/childActor")
  child1 ! DivideNumbers(4,0)

class ParentActor extends Actor{
  override def receive: Receive = {
    case CreateChildren =>
      context.actorOf(Props[ChildActor], "childActor")
  }
}

  class ChildActor extends Actor{
    override def receive: Receive = {
      case DivideNumbers(n,d) => println(n/d)

    }
  }

  actorSystem.terminate()
}

但是当我没有创造出儿童演员并且有类似的东西时,我看不到例外。

val actorSystem = ActorSystem("SupervisingActorSystem")
  val actor = actorSystem.actorOf(Props[ParentActor], "ParentActor")
  actor ! DivideNumbers(4, 2)

  class ParentActor extends Actor {
    override def receive: Receive = {
      case DivideNumbers(n, d) => println(n / d)
      //case DivideNumbers(n, d) => throw new Exception
      //Even this doesn't throw an exception
    }
  }

  actorSystem.terminate()

1. 为什么我没有看到例外,我是不是错过了什么?
2. 这背后的原因是什么 行为?
3. 当我们 只有一个演员没有孩子?