function getArrayFromQuerySnapshot(querySnapshot) {
	const arr = [];
	querySnapshot.forEach(doc => {
		// doc.data() has to be after doc.id because docs can have `id` key in them which
		// should override the explicit `id` being set
		arr.push({
			id: doc.id,
			...doc.data()
		});
		//   documentCache[doc.id] = doc.data()
	});
	return arr;
}
Converts a firestore query snapshot into native array
@param {snapshot} querySnapshot Snapshot object returned by a firestore query