using scalaj.http.Http makes message sending break

Master.scala

import akka.actor.{ActorSystem, Props, Actor}
import scalaj.http.Http

case object Start

class Master extends Actor {
  val worker = context.actorOf(Props[Worker], name = "worker")

  def receive = {
    case Start =>
      worker ! Start

    case s:String => println(s)

    case _ =>
      println("default")
  }
}

class Worker extends Actor {
  def receive = {
    case Start =>
//      val data = Http("http://google.com/").asString
      sender ! "foo"
  }
}

object TestApp extends App {
  val system = ActorSystem("TestApp")

  val master = system.actorOf(Props[Master], "master")

  master ! Start

  system.shutdown()
}