NoClassDefFoundError may be thrown after attempting to cast null cast to Nothing in REPL

[Glavo]

(Reviews from #4410)
NullPointerException was thrown when I tried to convert null to Nothing in REPL:

scala> val a = (null.asInstanceOf[Nothing]: Null) 
java.lang.NullPointerException
	at rs$line$1$.<init>(rs$line$1:1)
	at rs$line$1$.<clinit>(rs$line$1)
	at rs$line$1.aShow(rs$line$1)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at dotty.tools.repl.Rendering.valueOf(Rendering.scala:58)
	at dotty.tools.repl.Rendering.renderVal(Rendering.scala:79)
	at dotty.tools.repl.ReplDriver.displayMembers$3$$anonfun$3(ReplDriver.scala:284)
	at scala.collection.TraversableLike.$anonfun$map$1(TraversableLike.scala:234)
	at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:59)
	at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:52)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
	at scala.collection.TraversableLike.map(TraversableLike.scala:234)
	at scala.collection.TraversableLike.map$(TraversableLike.scala:227)
	at scala.collection.AbstractTraversable.map(Traversable.scala:104)
	at dotty.tools.repl.ReplDriver.displayMembers$7(ReplDriver.scala:284)
	at dotty.tools.repl.ReplDriver.displayDefinitions$$anonfun$3$$anonfun$2(ReplDriver.scala:311)
	at scala.Option.map(Option.scala:146)
	at dotty.tools.repl.ReplDriver.displayDefinitions$$anonfun$1(ReplDriver.scala:311)
	at dotty.tools.dotc.core.Periods.atPhase(Periods.scala:26)
	at dotty.tools.dotc.core.Phases.atPhase(Phases.scala:36)
	at dotty.tools.repl.ReplDriver.displayDefinitions(ReplDriver.scala:316)
	at dotty.tools.repl.ReplDriver.compile$$anonfun$2(ReplDriver.scala:241)
	at scala.util.Either.fold(Either.scala:188)
	at dotty.tools.repl.ReplDriver.compile(ReplDriver.scala:242)
	at dotty.tools.repl.ReplDriver.interpret(ReplDriver.scala:202)
	at dotty.tools.repl.ReplDriver.loop$1(ReplDriver.scala:150)
	at dotty.tools.repl.ReplDriver.runUntilQuit$$anonfun$1(ReplDriver.scala:154)
	at dotty.tools.repl.ReplDriver.withRedirectedOutput$$anonfun$2$$anonfun$1(ReplDriver.scala:163)
	at scala.util.DynamicVariable.withValue(DynamicVariable.scala:58)
	at scala.Console$.withErr(Console.scala:192)
	at dotty.tools.repl.ReplDriver.withRedirectedOutput$$anonfun$1(ReplDriver.scala:163)
	at scala.util.DynamicVariable.withValue(DynamicVariable.scala:58)
	at scala.Console$.withOut(Console.scala:163)
	at dotty.tools.repl.ReplDriver.withRedirectedOutput(ReplDriver.scala:163)
	at dotty.tools.repl.ReplDriver.runUntilQuit(ReplDriver.scala:154)
	at dotty.tools.repl.Main$.main(Main.scala:6)
	at dotty.tools.repl.Main.main(Main.scala)

But a is still defined and NoClassDefFoundError is thrown when use it:

scala> a 
java.lang.NoClassDefFoundError: Could not initialize class rs$line$1$
	at rs$line$2$.<init>(rs$line$2:1)
	at rs$line$2$.<clinit>(rs$line$2)
	at rs$line$2.res0Show(rs$line$2)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at dotty.tools.repl.Rendering.valueOf(Rendering.scala:58)
	at dotty.tools.repl.Rendering.renderVal(Rendering.scala:79)
	at dotty.tools.repl.ReplDriver.displayMembers$3$$anonfun$3(ReplDriver.scala:284)
	at scala.collection.TraversableLike.$anonfun$map$1(TraversableLike.scala:234)
	at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:59)
	at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:52)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
	at scala.collection.TraversableLike.map(TraversableLike.scala:234)
	at scala.collection.TraversableLike.map$(TraversableLike.scala:227)
	at scala.collection.AbstractTraversable.map(Traversable.scala:104)
	at dotty.tools.repl.ReplDriver.displayMembers$7(ReplDriver.scala:284)
	at dotty.tools.repl.ReplDriver.displayDefinitions$$anonfun$3$$anonfun$2(ReplDriver.scala:311)
	at scala.Option.map(Option.scala:146)
	at dotty.tools.repl.ReplDriver.displayDefinitions$$anonfun$1(ReplDriver.scala:311)
	at dotty.tools.dotc.core.Periods.atPhase(Periods.scala:26)
	at dotty.tools.dotc.core.Phases.atPhase(Phases.scala:36)
	at dotty.tools.repl.ReplDriver.displayDefinitions(ReplDriver.scala:316)
	at dotty.tools.repl.ReplDriver.compile$$anonfun$2(ReplDriver.scala:241)
	at scala.util.Either.fold(Either.scala:188)
	at dotty.tools.repl.ReplDriver.compile(ReplDriver.scala:242)
	at dotty.tools.repl.ReplDriver.interpret(ReplDriver.scala:202)
	at dotty.tools.repl.ReplDriver.loop$1(ReplDriver.scala:150)
	at dotty.tools.repl.ReplDriver.runUntilQuit$$anonfun$1(ReplDriver.scala:154)
	at dotty.tools.repl.ReplDriver.withRedirectedOutput$$anonfun$2$$anonfun$1(ReplDriver.scala:163)
	at scala.util.DynamicVariable.withValue(DynamicVariable.scala:58)
	at scala.Console$.withErr(Console.scala:192)
	at dotty.tools.repl.ReplDriver.withRedirectedOutput$$anonfun$1(ReplDriver.scala:163)
	at scala.util.DynamicVariable.withValue(DynamicVariable.scala:58)
	at scala.Console$.withOut(Console.scala:163)
	at dotty.tools.repl.ReplDriver.withRedirectedOutput(ReplDriver.scala:163)
	at dotty.tools.repl.ReplDriver.runUntilQuit(ReplDriver.scala:154)
	at dotty.tools.repl.Main$.main(Main.scala:6)
	at dotty.tools.repl.Main.main(Main.scala)

This behavior is beyond my expectation!

[allanrenucci]

Closing in favor of #4416