src/node/heart.ts/Heart/beat
class Heart:  public async beat(): Promise<void> {
    if (this.alive()) {
      return
    }

    logger.trace("heartbeat")
    this.lastHeartbeat = Date.now()
    if (typeof this.heartbeatTimer !== "undefined") {
      clearTimeout(this.heartbeatTimer)
    }
    this.heartbeatTimer = setTimeout(() => heartbeatTimer(this.isActive, this.beat), this.heartbeatInterval)
    try {
      return await fs.writeFile(this.heartbeatPath, "")
    } catch (error: any) {
      logger.warn(error.message)
    }
  }