🐛 [Bug]: 表尾合并时，返回{ rowspan: 0, colspan: 0 }并不能隐藏单元格

[Godknow]

Version

3.20

Vue Version

3.20

Link to minimal reproduction

表尾合并时，返回{ rowspan: 0, colspan: 0 }并不能隐藏单元格，官方例子中也一样，

，本来就是这么用的么？

Step to reproduce

官方例子：
http://opentiny.design/tiny-vue/zh-CN/os-theme/components/grid-footer#footer-footer-row-or-column-span

What is expected

返回{ rowspan: 0, colspan: 0 }能隐藏单元格。

What is actually happening

No response

What is your project name

个人毕业设计

Any additional comments (optional)

No response

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Title: 🐛 [Bug]: When merging table tails, returning { rowspan: 0, colspan: 0 } does not hide cells

[gimmyhehe]

@Godknow rowspan和colspan是与原生table表现一致的，因此就算设置为0也隐藏不了，此处官网demo也有问题，后续我们优化一下。

如果你不需要那么多单元格，你可以将前面的单元格的colspan设置大一些，然后将对应数据放到前面的单元格。

以下是示例与代码：

<template>
  <tiny-grid
    :data="tableData"
    border
    show-footer
    :footer-method="footerMethod"
    :footer-span-method="footerRowspanMethod"
  >
    <tiny-grid-column type="index" width="60"></tiny-grid-column>
    <tiny-grid-column type="selection" width="60"></tiny-grid-column>
    <tiny-grid-column field="name" title="公司名称"></tiny-grid-column>
    <tiny-grid-column field="employees" title="员工数"></tiny-grid-column>
    <tiny-grid-column field="createdDate" title="创建日期"></tiny-grid-column>
    <tiny-grid-column field="city" title="城市"></tiny-grid-column>
  </tiny-grid>
</template>

<script lang="jsx">
import { TinyGrid, TinyGridColumn } from '@opentiny/vue'

export default {
  components: {
    TinyGrid,
    TinyGridColumn
  },
  data() {
    return {
      tableData: [
        {
          id: '1',
          name: 'GFD科技YX公司',
          city: '福州',
          employees: 800,
          createdDate: '2014-04-30 00:56:00'
        },
        {
          id: '2',
          name: 'WWW科技YX公司',
          city: '深圳',
          employees: 300,
          createdDate: '2016-07-08 12:36:22'
        },
        {
          id: '3',
          name: 'RFV有限责任公司',
          city: '中山',
          employees: 1300,
          createdDate: '2014-02-14 14:14:14'
        },
        {
          id: '4',
          name: 'TGB科技YX公司',
          city: '龙岩',
          employees: 360,
          createdDate: '2013-01-13 13:13:13'
        },
        {
          id: '5',
          name: 'YHN科技YX公司',
          city: '韶关',
          employees: 810,
          createdDate: '2012-12-12 12:12:12'
        },
        {
          id: '6',
          name: 'WSX科技YX公司',
          city: '黄冈',
          employees: 800,
          createdDate: '2011-11-11 11:11:11'
        },
        {
          id: '7',
          name: 'KBG物业YX公司',
          city: '赤壁',
          employees: 400,
          createdDate: '2016-04-30 23:56:00'
        },
        {
          id: '8',
          name: '深圳市福德宝网络技术YX公司',
          city: '厦门',
          employees: 540,
          createdDate: '2016-06-03 13:53:25'
        }
      ]
    }
  },
  methods: {
    footerMethod({ columns, data }) {
      return [
        columns.map((column, columnIndex) => {
          if (columnIndex === 0) {
            return '全部的员工数量'
          }

          if (columnIndex === 1) {
            return data.map((item) => item.employees).reduce((acc, item) => acc + item)
          }

          return null
        }),
        columns.map((column, columnIndex) => {
          if (columnIndex === 0) {
            return null
          }

          if (column.property === 'employees') {
            return null
          }

          return null
        })
      ]
    },
    footerRowspanMethod({ $rowIndex, columnIndex }) {
      if ($rowIndex === 0) {
        if (columnIndex === 0) {
          return { rowspan: 2, colspan: 2 }
        }

        if (columnIndex === 1) {
          return { rowspan: 2, colspan: 4 }
        }
      }
    }
  }
}
</script>