message: make group use the optional type.
diff: @@ -208,8 +208,8 @@ export class ConfigGroup extends ConfigFile {
  * @param {string} [group = 'default'] The group.
  * @returns {ConfigContents} The contents.
  */
  - public getGroup(group?: string): Optional<ConfigContents> {
  - return get(this.getContents(), group || this.defaultGroup);
  + public getGroup(group: Optional<string> = this.defaultGroup): Optional<ConfigContents> {
  + return get(this.getContents(), group);
  }
  /**
  