Monad IO catchAll operator behave

Question

I´m learning the monad IO of scalaZ and I cannot understand how catchAll and catchSome operators works. I was expecting so see a behave like the onError or onErrorrResumeNext of RxJava, but instead is not catching the throwable, and it´s just breaking the test and throwing the NullPointerException..

Here my two examples

  @Test
  def catchAllOperator(): Unit = {
    val errorSentence: IO[Throwable, String] =
      IO.point[Throwable, String](null)
        .map(value => value.toUpperCase())
        .catchAll(error => IO.fail(error))
    println(unsafePerformIO(errorSentence))

  }

And catchSome example

  @Test
  def catchSomeOperator(): Unit = {
    val errorFunction = new PartialFunction[Throwable /*Entry type*/ , IO[Throwable, String] /*Output type*/ ] {

      override def isDefinedAt(x: Throwable): Boolean = x.isInstanceOf[NullPointerException]

      override def apply(v1: Throwable): IO[Throwable, String] = IO.point("Default value")
    }

    val errorSentence = IO.point[Throwable, String](null)
      .map(value => value.toUpperCase())
      .catchSome(errorFunction)
    println(unsafePerformIO(errorSentence))

  }

Any idea what I´m doing wrong?.

Regards