Fix wrong extractor

Author: nicolasstucki

library/src/scala/tasty/util/ShowSourceCode.scala

@@ -541,8 +541,8 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
         printTypeTree(lo)
         this += " <: "
         printTypeTree(hi)
-      case tpt@Type() =>
-        printType(tpt)
+      case tpt @ TypeTree() =>
+        printTypeTree(tpt)
     }
 
     def printTypeTree(tree: TypeTree): Buffer = tree match {