structuredClone preserves Error cause references and drops falsy causes

Description

The React Native structuredClone polyfill passes Error.cause through by reference instead of cloning it, and only copies the property when its value is truthy. Object causes therefore remain shared with the input; a circular cause points back to the original Error; and valid falsy causes such as false disappear.

Expected behavior

An own cause property should be cloned recursively, retain its non-enumerable Error property descriptor, preserve circular/shared identity within the clone, and keep falsy values. Node's native structuredClone follows this behavior.

React Native Version

0.87.1 and current main

Affected Platforms

JavaScript runtime - All

まず React Native の structuredClone polyfill を見つけ、Error.cause をどのように扱っているかを確認します。Node のネイティブな structuredClone と動作を比較し、再帰的なクローン、保持された循環/共有アイデンティティ、非列挙プロパティの descriptor、falsy な cause を示すテストカバレッジを追加します。