Nothing Scala gotcha

nothing.scala

\/-(1).fold(
  sys.exit(0),
  t => { System.err.println(t); sys.exit(1) })

// this doesn't do the right thing, why?
// because it should be
\/-(1).fold(
  _ => sys.exit(0),
  t => { System.err.println(t); sys.exit(1) })
  
// But the compiler doesn't complain in the first case because `sys.exit(0)` has type `Nothing` and will gladly pass it as `Int => A`.  
// add "-Ywarn-dead-code" to avoid this issue