NPE when fork := true

[metasim]

Not sure if fork := true is even a valid setting, but at any rate, it causes tut to trigger an NPE.

[error] Exception in thread "main" java.lang.NullPointerException
[error] 	at scala.reflect.internal.SymbolTable.exitingPhase(SymbolTable.scala:256)
[error] 	at scala.tools.nsc.interpreter.IMain$Request.x$20$lzycompute(IMain.scala:896)
[error] 	at scala.tools.nsc.interpreter.IMain$Request.x$20(IMain.scala:895)
[error] 	at scala.tools.nsc.interpreter.IMain$Request.headerPreamble$lzycompute(IMain.scala:895)
[error] 	at scala.tools.nsc.interpreter.IMain$Request.headerPreamble(IMain.scala:895)
[error] 	at scala.tools.nsc.interpreter.IMain$Request$Wrapper.preamble(IMain.scala:918)
[error] 	at scala.tools.nsc.interpreter.IMain$CodeAssembler$$anonfun$apply$23.apply(IMain.scala:1337)
[error] 	at scala.tools.nsc.interpreter.IMain$CodeAssembler$$anonfun$apply$23.apply(IMain.scala:1336)
[error] 	at scala.tools.nsc.util.package$.stringFromWriter(package.scala:64)
[error] 	at scala.tools.nsc.interpreter.IMain$CodeAssembler$class.apply(IMain.scala:1336)
[error] 	at scala.tools.nsc.interpreter.IMain$Request$Wrapper.apply(IMain.scala:908)
[error] 	at scala.tools.nsc.interpreter.IMain$Request.compile$lzycompute(IMain.scala:1002)
[error] 	at scala.tools.nsc.interpreter.IMain$Request.compile(IMain.scala:997)
[error] 	at scala.tools.nsc.interpreter.IMain.compile(IMain.scala:579)
[error] 	at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:567)
[error] 	at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:565)
[error] 	at tut.Tut$$anonfun$tut$Tut$$interp$1$$anonfun$apply$16$$anonfun$apply$17$$anonfun$apply$18$$anonfun$apply$19$$anonfun$apply$20.apply(Tut.scala:50)
[error] 	at tut.Tut$$anonfun$tut$Tut$$interp$1$$anonfun$apply$16$$anonfun$apply$17$$anonfun$apply$18$$anonfun$apply$19$$anonfun$apply$20.apply(Tut.scala:50)
[error] 	at tut.Zed$IO$$anonfun$apply$5.apply(Zed.scala:86)
[error] 	at tut.Zed$IO$$anonfun$apply$5.apply(Zed.scala:86)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$IOOps$$anonfun$withOut$1$$anonfun$apply$8.apply(Zed.scala:101)
[error] 	at tut.Zed$IOOps$$anonfun$withOut$1$$anonfun$apply$8.apply(Zed.scala:101)
[error] 	at scala.util.DynamicVariable.withValue(DynamicVariable.scala:58)
[error] 	at scala.Console$.withOut(Console.scala:65)
[error] 	at tut.Zed$IOOps$$anonfun$withOut$1.apply(Zed.scala:101)
[error] 	at tut.Zed$IOOps$$anonfun$withOut$1.apply(Zed.scala:101)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$map$1.apply(Zed.scala:31)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$State$$anonfun$flatMap$1.apply(Zed.scala:32)
[error] 	at tut.Zed$IOOps.unsafePerformIO(Zed.scala:99)
[error] 	at tut.TutMain$.main(TutMain.scala:8)
[error] 	at tut.TutMain.main(TutMain.scala)