Revert "Only expand the tree if no errors are reported."

This reverts commit 0b0e616.

Author: Sebastian Nadorp

compiler/src/dotty/tools/dotc/ast/DesugarEnums.scala

@@ -64,7 +64,8 @@ object DesugarEnums {
   }
 
   /** A type tree referring to `enumClass` */
-  def enumClassRef(implicit ctx: Context) = TypeTree(enumClass.typeRef)
+  def enumClassRef(implicit ctx: Context) =
+    if (enumClass.exists) TypeTree(enumClass.typeRef) else TypeTree()
 
   /** Add implied flags to an enum class or an enum case */
   def addEnumFlags(cdef: TypeDef)(implicit ctx: Context) =

compiler/src/dotty/tools/dotc/typer/Namer.scala

@@ -415,7 +415,7 @@ class Namer { typer: Typer =>
 
   /** Expand tree and store in `expandedTree` */
   def expand(tree: Tree)(implicit ctx: Context): Unit = tree match {
-    case mdef: DefTree if !ctx.reporter.hasErrors =>
+    case mdef: DefTree =>
       val expanded = desugar.defTree(mdef)
       typr.println(i"Expansion: $mdef expands to $expanded")
       if (expanded ne mdef) mdef.pushAttachment(ExpandedTree, expanded)