refactor objects

internal/object/error.go

@@ -18,7 +18,8 @@ func (e Error) Inspect() string {
 	return "Error: " + e.Message
 }
 
-func (e Error) Clone() Object {
+// Copy implements the Copyable interface
+func (e Error) Copy() Object {
 	return Error{Message: e.Message}
 }