src/vs/platform/backup/electron-main/backupMainService.ts/BackupMainService/validateEmptyWorkspaces
class BackupMainService:	private async validateEmptyWorkspaces(emptyWorkspaces: IEmptyWindowBackupInfo[]): Promise<IEmptyWindowBackupInfo[]> {
		if (!Array.isArray(emptyWorkspaces)) {
			return [];
		}

		const result: IEmptyWindowBackupInfo[] = [];
		const seenIds: Set<string> = new Set();

		// Validate Empty Windows
		for (const backupInfo of emptyWorkspaces) {
			const backupFolder = backupInfo.backupFolder;
			if (typeof backupFolder !== 'string') {
				return [];
			}

			if (!seenIds.has(backupFolder)) {
				seenIds.add(backupFolder);

				const backupPath = join(this.backupHome, backupFolder);
				if (await this.doHasBackups(backupPath)) {
					result.push(backupInfo);
				} else {
					await this.deleteStaleBackup(backupPath);
				}
			}
		}

		return result;
	}