Assertion Error When Using ForOf & this Keyword

[garbearrr]

Description

Similar to #1417
Map throws assertion error when attempting to extend map functionality in ForOf iteration.

Reproduction

map<T extends defined>(fn: (value: V, key: K, collection: this) => T): T[] {
	const arr: T[] = [];
	for (const [key, value] of this) {
		arr.push(fn(value, key, this));
	}
	return arr;
}

Error

> rbxtsc -w true 

Error: Assertion Failed! ForOf iteration type not implemented: this
This is a compiler bug! Please submit a bug report here:
https://github.com/roblox-ts/roblox-ts/issues
...

Node.js v19.8.1