如何删除Vue Chart数据点上的文本？

<template>
  <div>
    <canvas ref="chartCanvas"></canvas>
  </div>
</template>

<script>
import { Line } from 'vue-chartjs';

export default {
  extends: Line,
  mounted() {
    this.renderChart({
      labels: ['January', 'February', 'March', 'April', 'May', 'June', 'July'],
      datasets: [{
        label: 'Data',
        data: [10, 20, 30, 40, 50, 60, 70]
      }]
    }, {
      tooltips: {
        callbacks: {
          tooltipLabel: (tooltipItem, data) => {
            // 判断数据点的索引
            if (tooltipItem.index === 2) {
              // 返回空字符串以隐藏文本
              return '';
            } else {
              // 返回默认文本
              return data.datasets[tooltipItem.datasetIndex].data[tooltipItem.index];
            }
          }
        }
      }
    });
  }
};
</script>