Two examplars of type-dependent type bring REPL to runtime error

[scalasolist]

paste into REPL:

trait Parent {
  sealed trait HNil
  object HNil extends HNil
}

trait Single extends Parent {
  val u = HNil
}

Try the following code:

scala> object X extends Single
defined module X
scala> object Y extends Single
defined module Y
scala> X.u
val res0: X.HNil.type = Parent$HNil$@2b14d160
scala> Y.u

get the error:

java.lang.IncompatibleClassChangeError: Interface method reference: Parent.HNil()LParent$HNil$;, is in an indirect superinterface of Y$
    at Y$.HNil(<console>:4)
    at Single.initial$u(AbsHList.scala:46)
    at Y$.<init>(<console>:4)
    at Y$.<clinit>(<console>)
    at .<init>(<console>:6)
    at .<clinit>(<console>)
    at RequestResult$.<init>(<console>:3)
    at Reques...

I could not reproduce that error outside REPL in a standalone application

[2m]

Got the same error (still only in the REPL) with the following different sample:

scala> trait T(x: Int)
defined trait T
scala> trait U extends T
defined trait U
scala> class C extends U with T(22)
defined class C
scala> new C
java.lang.IncompatibleClassChangeError: Interface method reference: T.$init$()V, is in an indirect superinterface of C
        at C.<init>(<console>:6)
        at .<init>(<console>:8)
        at .<clinit>(<console>)
        at RequestResult$.<init>(<console>:3)
        at RequestResult$.<clinit>(<console>)
        at RequestResult$result(<console>)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflec...