# Important Notes

## Table of Contents
- [Overview](#overview)
- [Key Insights](#key-insights)

## Overview
This document captures critical insights and considerations for maintaining and ensuring the stability of the project.

## Key Insights
*   **ESLint v9+ Configuration**: ESLint v9 and later versions require a flat configuration file (e.g., [`eslint.config.js`](eslint.config.js:1)). If the project is not configured with `"type": "module"` in `package.json`, the ESLint config file itself may require CommonJS syntax to prevent Node.js module type warnings.
*   **Safer Property Checks**: Using [`Object.hasOwn()`](index.js:281) is preferred over `obj.hasOwnProperty()` for better code safety and to avoid potential issues, especially when dealing with objects that might have `hasOwnProperty` overridden or when working with untrusted data.