[Bug] render abnormal when value is empty string in pie chart

[skie1997]

Version

lastest

Link to Minimal Reproduction

visactor website

Steps to Reproduce

const spec = {
  type: 'pie',
  data: [
    {
      id: 'id0',
      values: [
        { type: 'oxygen', value: '' },
        { type: 'silicon', value: '27.72' },
        { type: 'aluminum', value: '8.13' },
        { type: 'iron', value: '5' },
        { type: 'calcium', value: '3.63' },
        { type: 'sodium', value: '2.83' },
        { type: 'potassium', value: '2.59' },
        { type: 'others', value: '3.5' }
      ]
    }
  ],
  outerRadius: 0.8,
  valueField: 'value',
  categoryField: 'type',
  title: {
    visible: true,
    text: 'Statistics of Surface Element Content'
  },
  legends: {
    visible: true,
    orient: 'left'
  },
  label: {
    visible: true
  },
  tooltip: {
    mark: {
      content: [
        {
          key: datum => datum['type'],
          value: datum => datum['value'] + '%'
        }
      ]
    }
  }
};

Current Behavior

Expected Behavior

Environment

- OS:
- Browser:
- Framework:

Any additional comments?

No response