Opaque type allows using AnyKind as a value type (AssertionError: Bad superClass)

[panacekcz]

minimized code

object O{
  opaque type T[X <: AnyKind] = X
}
def m(x: O.T[AnyKind]) = x

Crash output (click arrow to expand)

Error while emitting opaque-anykind.scala
exception occurred while compiling opaque-anykind.scala
java.lang.AssertionError: assertion failed: Bad superClass for class AnyKind: val <none> while compiling opaque-anykind.scala
Exception in thread "main" java.lang.AssertionError: assertion failed: Bad superClass for class AnyKind: val <none>
	at dotty.DottyPredef$.assertFail(DottyPredef.scala:17)
	at dotty.tools.backend.jvm.BTypesFromSymbols.setClassInfo(BTypesFromSymbols.scala:66)
	at dotty.tools.backend.jvm.BTypesFromSymbols.classBTypeFromSymbol$$anonfun$4(BTypesFromSymbols.scala:60)
	at scala.collection.mutable.HashMap.getOrElse(HashMap.scala:416)
	at dotty.tools.backend.jvm.BTypesFromSymbols.classBTypeFromSymbol(BTypesFromSymbols.scala:61)
	at dotty.tools.backend.jvm.BCodeHelpers$BCInnerClassGen.getClassBTypeAndRegisterInnerClass(BCodeHelpers.scala:229)
	at dotty.tools.backend.jvm.BCodeHelpers$JCommonBuilder.getClassBTypeAndRegisterInnerClass(BCodeHelpers.scala:440)
	at dotty.tools.backend.jvm.DottyBackendInterface.dotty$tools$backend$jvm$DottyBackendInterface$$anon$9$$_$primitiveOrClassToBType$3$$anonfun$3(DottyBackendInterface.scala:912)
	at scala.collection.immutable.HashMap.getOrElse(HashMap.scala:656)
	at dotty.tools.backend.jvm.DottyBackendInterface$$anon$9.primitiveOrClassToBType$1(DottyBackendInterface.scala:912)
	at dotty.tools.backend.jvm.DottyBackendInterface$$anon$9.toTypeKind(DottyBackendInterface.scala:931)
	at dotty.tools.backend.jvm.BCodeHelpers$BCInnerClassGen.toTypeKind(BCodeHelpers.scala:258)
	at dotty.tools.backend.jvm.BCodeHelpers$JCommonBuilder.toTypeKind(BCodeHelpers.scala:440)
	at dotty.tools.backend.jvm.BCodeHelpers$BCForwardersGen.$anonfun$1(BCodeHelpers.scala:313)
	at scala.collection.immutable.List.map(List.scala:219)
	at dotty.tools.backend.jvm.BCodeHelpers$BCForwardersGen.addForwarder(BCodeHelpers.scala:313)
	at dotty.tools.backend.jvm.BCodeHelpers$BCForwardersGen.addForwarders$$anonfun$2(BCodeHelpers.scala:393)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:305)
	at dotty.tools.backend.jvm.BCodeHelpers$BCForwardersGen.addForwarders(BCodeHelpers.scala:395)
	at dotty.tools.backend.jvm.BCodeHelpers$JCommonBuilder.addForwarders(BCodeHelpers.scala:440)
	at dotty.tools.backend.jvm.BCodeHelpers$JMirrorBuilder.genMirrorClass(BCodeHelpers.scala:488)
	at dotty.tools.backend.jvm.GenBCodePipeline$Worker1.visit(GenBCode.scala:208)
	at dotty.tools.backend.jvm.GenBCodePipeline$Worker1.run(GenBCode.scala:184)
	at dotty.tools.backend.jvm.GenBCodePipeline.buildAndSendToDisk(GenBCode.scala:514)
	at dotty.tools.backend.jvm.GenBCodePipeline.run(GenBCode.scala:480)
	at dotty.tools.backend.jvm.GenBCode.run(GenBCode.scala:51)
	at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:315)
	at scala.collection.immutable.List.map(List.scala:219)
	at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:316)
	at dotty.tools.backend.jvm.GenBCode.runOn(GenBCode.scala:55)
	at dotty.tools.dotc.Run.runPhases$4$$anonfun$4(Run.scala:167)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
	at dotty.tools.dotc.Run.runPhases$5(Run.scala:177)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:185)
	at dotty.runtime.function.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:64)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:192)
	at dotty.tools.dotc.Run.compileSources(Run.scala:129)
	at dotty.tools.dotc.Run.compile(Run.scala:112)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:36)
	at dotty.tools.dotc.Driver.process(Driver.scala:189)
	at dotty.tools.dotc.Driver.process(Driver.scala:158)
	at dotty.tools.dotc.Driver.process(Driver.scala:170)
	at dotty.tools.dotc.Driver.main(Driver.scala:197)
	at dotty.tools.dotc.Main.main(Main.scala)