joinRanges = (startRange, endRange) => {
	if (!endRange) return startRange;
	if (!startRange) return endRange;
	return [startRange[0], endRange[1]];
}
Helper function for joining two ranges into a single range. This is useful
when working with AST nodes, as it allows you to combine the ranges of child nodes
to create the range of the _parent node_.
@param {Range} startRange start range to join
@param {Range} endRange end range to join
@returns {Range} joined range
@example
```js
	const startRange = [0, 5];
	const endRange = [10, 15];
	const joinedRange = joinRanges(startRange, endRange);
	console.log(joinedRange); // [0, 15]
```