Assertion Error in the typer while inferring return type (parser stability)

[sir-wabbit]

def I0(I1: Int ) = I1
val I1 = I0(I0 i2
) => true

def I0(i1: Int) = i1
val i1 = I0( I0 i1
) => true

AE-cf6cdd19dd6230b2411b05591dcb89a7acb861db

---

exception occurred while typechecking test.scala
exception occurred while compiling test.scala
java.lang.AssertionError: assertion failed: Mode(Type,ImplicitsEnabled,InferringReturnType) while compiling test.scala
Exception in thread "main" java.lang.AssertionError: assertion failed: Mode(Type,ImplicitsEnabled,InferringReturnType)
	at scala.Predef$.assert(Predef.scala:223)
	at dotty.tools.dotc.ast.desugar$.apply(Desugar.scala:1356)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2054)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2066)
	at dotty.tools.dotc.typer.ProtoTypes$FunProto.$anonfun$typedArg$1(ProtoTypes.scala:333)
	at dotty.tools.dotc.typer.ProtoTypes$FunProto.cacheTypedArg(ProtoTypes.scala:296)
	at dotty.tools.dotc.typer.ProtoTypes$FunProto.typedArg(ProtoTypes.scala:333)
	at dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:753)
	at dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:751)
	at dotty.tools.dotc.typer.Applications$Application.addTyped$1(Applications.scala:519)
	at dotty.tools.dotc.typer.Applications$Application.matchArgs(Applications.scala:562)
	at dotty.tools.dotc.typer.Applications$Application.init(Applications.scala:340)
	at dotty.tools.dotc.typer.Applications$TypedApply.<init>(Applications.scala:654)
	at dotty.tools.dotc.typer.Applications$ApplyToUntyped.<init>(Applications.scala:752)
	at dotty.tools.dotc.typer.Applications.simpleApply$1(Applications.scala:814)
	at dotty.tools.dotc.typer.Applications.$anonfun$typedApply$9(Applications.scala:843)
	at dotty.tools.dotc.typer.Typer.tryEither(Typer.scala:2192)
	at dotty.tools.dotc.typer.Applications.$anonfun$typedApply$1(Applications.scala:844)
	at dotty.tools.dotc.util.Stats$.track(Stats.scala:37)
	at dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:783)
	at dotty.tools.dotc.typer.Applications.typedApply(Applications.scala:889)
	at dotty.tools.dotc.typer.Applications.typedApply$(Applications.scala:781)
	at dotty.tools.dotc.typer.Typer.typedApply(Typer.scala:87)