REPL crashes on val _ = ???

[griggt]

Compiler version

3.1.2-RC2

Minimized code

scala> val _ = ???

Output

scala> val _ = ???
Exception in thread "main" scala.NotImplementedError: an implementation is missing
	at scala.Predef$.$qmark$qmark$qmark(Predef.scala:344)
	at rs$line$1$.<clinit>(rs$line$1:1)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:348)
	at dotty.tools.repl.Rendering.load$1(Rendering.scala:147)
	at dotty.tools.repl.Rendering.forceModule(Rendering.scala:149)
	at dotty.tools.repl.ReplDriver.extractAndFormatMembers$1(ReplDriver.scala:337)
	at dotty.tools.repl.ReplDriver.renderDefinitions$$anonfun$2(ReplDriver.scala:358)
	at scala.Option.map(Option.scala:242)
	at dotty.tools.repl.ReplDriver.renderDefinitions(ReplDriver.scala:361)
	at dotty.tools.repl.ReplDriver.compile$$anonfun$2(ReplDriver.scala:280)
	at scala.util.Either.fold(Either.scala:189)
	at dotty.tools.repl.ReplDriver.compile(ReplDriver.scala:296)
	at dotty.tools.repl.ReplDriver.interpret(ReplDriver.scala:230)
	at dotty.tools.repl.ReplDriver.loop$1(ReplDriver.scala:162)
	at dotty.tools.repl.ReplDriver.runUntilQuit$$anonfun$1(ReplDriver.scala:165)
	at dotty.tools.repl.ReplDriver.withRedirectedOutput(ReplDriver.scala:186)
	at dotty.tools.repl.ReplDriver.runBody$$anonfun$1(ReplDriver.scala:174)
	at dotty.tools.runner.ScalaClassLoader$.asContext(ScalaClassLoader.scala:80)
	at dotty.tools.repl.ReplDriver.runBody(ReplDriver.scala:174)
	at dotty.tools.repl.ReplDriver.runUntilQuit(ReplDriver.scala:165)
	at dotty.tools.repl.ReplDriver.tryRunning(ReplDriver.scala:127)
	at dotty.tools.repl.Main$.main(Main.scala:6)
	at dotty.tools.MainGenericRunner$.run$1(MainGenericRunner.scala:192)
	at dotty.tools.MainGenericRunner$.main(MainGenericRunner.scala:267)
	at dotty.tools.MainGenericRunner.main(MainGenericRunner.scala)

Expectation

Should render the error message, but not crash.

scala> val _ = ???
scala.NotImplementedError: an implementation is missing
  at scala.Predef$.$qmark$qmark$qmark(Predef.scala:344)
  ... 57 elided

Notes

Occurs whenever the RHS throws any non-fatal subclass of j.l.Error, e.g. val _ = assert(false) also crashes.