fixup! [HashTreeCollections] Add TreeDictionary.combining(_:by:)

Author: lorentey

Sources/HashTreeCollections/HashNode/_HashNode+Subtree Removals.swift

@@ -67,7 +67,7 @@ extension _HashNode {
 extension _HashNode {
   @inlinable
   internal func removing(
-    _ level: _Level, _ bucket: _Bucket
+    _ level: _HashLevel, _ bucket: _Bucket
   ) -> (removed: Builder, replacement: Builder) {
     read { handle in
       assert(!handle.isCollisionNode)
@@ -92,7 +92,7 @@ extension _HashNode {
   }
 }
 
-extension _Node {
+extension _HashNode {
   @inlinable
   internal mutating func remove(
     _ level: _HashLevel, at path: _UnsafePath