src/vs/platform/userDataSync/common/userDataSyncService.ts/ManualSyncTask/preview
class ManualSyncTask:	async preview(): Promise<[SyncResource, ISyncResourcePreview][]> {
		try {
			if (this.isDisposed) {
				throw new Error('Disposed');
			}
			if (!this.previewsPromise) {
				this.previewsPromise = createCancelablePromise(token => this.getPreviews(token));
			}
			if (!this.previews) {
				this.previews = await this.previewsPromise;
			}
			return this.previews;
		} catch (error) {
			this.logService.error(error);
			throw error;
		}
	}