Class AssetBucket: assets: Map<string, Asset<D>> waiters: KEventHandler<any> errorWaiters: KEventHandler<any> lastUID: number add(name: string | null, loader: Promise<D>) => Asset<D> addLoaded(name: string | null, data: D) => Asset<D> get(handle: string) => Asset<D> | undefined progress() => number getFailedAssets() => [string, Asset<D>][] waitFor(name: string, timeout: number) => PromiseLike<D>