stat(name) {
    const file = this.files.get(name);
    if (file === undefined) {
      return undefined;
    }
    return {
      type: file.type,
      mode: file.mode,
      date: file.date,
      comment: file.comment,
    };
  }
@param {string} name
@returns {import('./types.js').ArchivedStat=}