Babel Plugin for idx Utility

babel-plugin-idx is a Babel plugin designed to transform usages of the `idx` utility function into explicit null-checking code. The `idx` utility, now deprecated and unmaintained, was created by Facebook to safely access deeply nested properties on objects and arrays where intermediate properties might be `null` or `undefined`, preventing `TypeError` exceptions. The plugin effectively replaces calls like `idx(props, _ => _.user.friends[0].friends)` with verbose but safe conditional expressions, optimizing performance by removing the need for a runtime `idx` function. The current stable version is 3.0.3, but the module is no longer receiving updates. Its primary differentiator was providing safe property access similar to the now-standard optional chaining (`?.`) operator, though with a key difference: `idx` returns `null` or `undefined` for intermediate `null`/`undefined` values, while optional chaining consistently resolves to `undefined`. This plugin is essential for `idx` to function correctly and efficiently, as the `idx` runtime function is purely illustrative.