code: func (c *Chain) WaitReady() error {
  	if err := c.isRunning(); err != nil {
  		return err
  	}
  
  	select {
  	case c.submitC <- nil:
  	case <-c.doneC:
  		return errors.Errorf("chain is stopped")
  	}
  
  	return nil
  }
docs: // WaitReady blocks when the chain:
  // - is catching up with other nodes using snapshot
  //
  // In any other case, it returns right away.