code: func (r *GetUtxoRequest) deliver(report *SpendReport, err error) {
  	select {
  	case r.resultChan <- &getUtxoResult{report, err}:
  	default:
  		log.Warnf("duplicate getutxo result delivered for "+
  			"outpoint=%v, spend=%v, err=%v",
  			r.Input.OutPoint, report, err)
  	}
  }
docs: // deliver tries to deliver the report or error to any subscribers. If
  // resultChan cannot accept a new update, this method will not block.