perf: toImmutable returns identity if already frozen

Skip cloning if input is already frozen - assumes if top-level
is frozen, entire DS is frozen (reasonable contract in practice).

Author: jasonkuhrt

src/domains/group/__.ts

@@ -175,6 +175,7 @@ export const cloneToMut = <$Group extends Any>(group: $Group): cloneToMut<$Group
  * ```
  */
 export const toImmutable = <$Group extends AnyMut>(group: $Group): toImmutable<$Group> => {
+  if (Object.isFrozen(group)) return group as any
   const result: AnyMut = {}
   for (const k in group) {
     result[k] = Obj.toImmutableMut([...(group[k] as any[])]) as any

src/domains/obj/mutability.ts

@@ -49,7 +49,7 @@ export interface ErrorMutableInputImmutableOutput extends
  * ```
  */
 export const toImmutable = <$obj extends object>(obj: $obj): toImmutable<$obj> => {
-  // todo: copy trait instead of hardcoded copy logic here
+  if (Object.isFrozen(obj)) return obj as toImmutable<$obj>
   const copy = (Array.isArray(obj) ? [...obj] : { ...obj }) as $obj
   return toImmutableMut(copy)
 }