Confirm that an exception is not lost with EitherT over Future when doing flatMapF and valueOrF

EitherTFutureTest.scala

package ca.vgorcinschi.cats

import cats.data.EitherT
import cats.implicits._

import java.io.IOException
import scala.concurrent.Future
import scala.util.{Failure, Success}

object EitherTFutureTest extends App {
  import concurrent.ExecutionContext.Implicits.global

  val externalFailedCall: Future[Unit] = Future.failed(new IOException("boom"))
  val externalSuccessfulCall: Future[Unit] = Future.unit

  def methodUnderTest: Future[Int] = {
    val either: Either[Exception, Int] = 1.asRight
    EitherT
      .fromEither[Future](either)
      .flatMap(_ => EitherT.right[Throwable](externalFailedCall))
      .flatMapF(_ => Future.successful(either))
      .valueOrF(exc => Future.failed(exc))
  }

  methodUnderTest onComplete {
    case Success(value) =>
      println(s"Successfully printed $value!")
    case Failure(exception) => System.err.println(s"Oops: ${exception.getStackTrace.mkString("\n")}")
  }
  Thread.sleep(2000)
}