Flatten React Router routes into one array

flattenRoutes.ts

import { RouteConfig } from "react-router-config";

function flattenRoutes(routes: RouteConfig[]): RouteConfig[] {
	return [
		...routes,
		...routes.reduce<RouteConfig[]>(
			(accum, route) => [...accum, ...(route.routes ? flattenRoutes(route.routes) : [])],
			[]
		),
	];
}