PolymorphismBoxing for Any/Nothing (#458)

Author: b-studios

effekt/shared/src/main/scala/effekt/core/PolymorphismBoxing.scala

@@ -330,6 +330,8 @@ object PolymorphismBoxing extends Phase[CoreTransformed, CoreTransformed] {
     case (unboxed, _: ValueType.Var) if box.isDefinedAt(unboxed) => BoxCoercer(unboxed)
     case (boxed, unboxed) if box.isDefinedAt(unboxed) && box(unboxed).tpe == boxed => UnboxCoercer(unboxed)
     case (_: ValueType.Var, unboxed) if box.isDefinedAt(unboxed) => UnboxCoercer(unboxed)
+    case (unboxed, core.Type.TTop) if box.isDefinedAt(unboxed) => BoxCoercer(unboxed)
+    case (core.Type.TBottom, unboxed) if box.isDefinedAt(unboxed) => UnboxCoercer(unboxed)
     case _ =>
       //Context.warning(s"Coercing ${PrettyPrinter.format(from)} to ${PrettyPrinter.format(to)}")
       new IdentityCoercer(from, to)