src/vs/platform/instantiation/common/graph.ts/Graph/_findCycle
class Graph:	private _findCycle(node: Node<T>, seen: Set<string>): string | undefined {
		for (let [id, outgoing] of node.outgoing) {
			if (seen.has(id)) {
				return [...seen, id].join(' -> ');
			}
			seen.add(id);
			const value = this._findCycle(outgoing, seen);
			if (value) {
				return value;
			}
			seen.delete(id);
		}
		return undefined;
	}