src/node/wrapper.ts/ParentProcess/start
class ParentProcess:  public start(args: DefaultedArgs): Promise<void> {
    // Our logger was created before we parsed CLI arguments so update the level
    // in case it has changed.
    this.logger.level = logger.level

    // Store for relaunches.
    this.args = args
    if (!this.started) {
      this.started = this._start()
    }
    return this.started
  }