crash on compilable code: assertion failed: dotty.tools.dotc.core.Scopes$MutableScope

[helloqirun]

scalac compiles but dotc crashes.

$ dotc -version

Dotty compiler version 0.5.0-bin-SNAPSHOT-git-4fefb64 -- Copyright 2002-2017, LAMP/EPFL

$ dotc abc.scala

-- [E006] Unbound Identifier Error: abc.scala:5:5 ------------------------------
5 |    @annot class Silly {}
  |     ^^^^^
  |     not found: type annot

longer explanation available when compiling with `-explain`

exception occurred while typechecking abc.scala

exception occurred while compiling abc.scala
Exception in thread "main" java.lang.AssertionError: assertion failed: dotty.tools.dotc.core.Scopes$MutableScope@3c7f66c4
	at dotty.DottyPredef$.assertFail(DottyPredef.scala:39)
	at dotty.tools.dotc.typer.NamerContextOps.denotNamed(Namer.scala:51)
	at dotty.tools.dotc.typer.Typer.loop$1(Typer.scala:271)
	at dotty.tools.dotc.typer.Typer.findRef$1(Typer.scala:334)
	at dotty.tools.dotc.typer.Typer.op$1(Typer.scala:353)
	at dotty.tools.dotc.typer.Typer.typedIdent(Typer.scala:102)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:1622)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:1689)
	at dotty.tools.dotc.typer.Typer.op$40(Typer.scala:1707)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:1703)
	at dotty.tools.dotc.typer.Typer.typedType(Typer.scala:1766)
	at dotty.tools.dotc.typer.Typer.op$6(Typer.scala:475)
	at dotty.tools.dotc.typer.Typer.typedNew(Typer.scala:456)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:1645)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:1690)
	at dotty.tools.dotc.typer.Typer.op$40(Typer.scala:1707)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:1703)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:1764)
	at dotty.tools.dotc.typer.Typer.typeSelectOnTerm$1(Typer.scala:397)
<snipped>

$ cat abc.scala

object test {
  class annot extends scala.annotation.Annotation
  def foo = {
    def bar(i: Int): Int = i
    @annot class Silly {}
    bar(5)
  }
}