src/vs/platform/instantiation/common/instantiationService.ts/InstantiationService/_safeCreateAndCacheServiceInstance
class InstantiationService:	private _safeCreateAndCacheServiceInstance<T>(id: ServiceIdentifier<T>, desc: SyncDescriptor<T>, _trace: Trace): T {
		if (this._activeInstantiations.has(id)) {
			throw new Error(`illegal state - RECURSIVELY instantiating service '${id}'`);
		}
		this._activeInstantiations.add(id);
		try {
			return this._createAndCacheServiceInstance(id, desc, _trace);
		} finally {
			this._activeInstantiations.delete(id);
		}
	}