使用Element的table合并单元格的问题（合并行）

目标样式:

 官网案例：

<el-table
      :data="tableData"
      :span-method="arraySpanMethod"
      border
      style=" 100%">
<el-table-column
        prop="id"
        label="ID"
        width="180">
      </el-table-column>
      <el-table-column
        prop="name"
        label="姓名">
      </el-table-column>
      <el-table-column
        prop="amount1"
        sortable
        label="数值 1">
      </el-table-column>
      <el-table-column
        prop="amount2"
        sortable
        label="数值 2">
      </el-table-column>
      <el-table-column
        prop="amount3"
        sortable
        label="数值 3">
      </el-table-column>
    </el-table>

<script>
  export default {
    data() {
      return {
        tableData: [{
          id: '12987122',
          name: '王小虎',
          amount1: '234',
          amount2: '3.2',
          amount3: 10
        }, {
          id: '12987123',
          name: '王小虎',
          amount1: '165',
          amount2: '4.43',
          amount3: 12
        }, {
          id: '12987124',
          name: '王小虎',
          amount1: '324',
          amount2: '1.9',
          amount3: 9
        }, {
          id: '12987125',
          name: '王小虎',
          amount1: '621',
          amount2: '2.2',
          amount3: 17
        }, {
          id: '12987126',
          name: '王小虎',
          amount1: '539',
          amount2: '4.1',
          amount3: 15
        }]
      };
    },
    methods: {
      arraySpanMethod({ row, column, rowIndex, columnIndex }) {
        if (rowIndex % 2 === 0) {
          if (columnIndex === 0) {
            return [1, 2];
          } else if (columnIndex === 1) {
            return [0, 0];
          }
        }
      },

      
    }
  };
</script>

但是在项目会遇到这种情况：

 合并的两行会出现高度不一致的情况

代码：

objectSpanMethod({ row, column, rowIndex, columnIndex }){
        if (rowIndex === 2 || rowIndex === 3) {
          let len = Object.keys(row).length
          if(columnIndex !== 0){
            return [1, len];
          }
        }
      },

解决方法：

不需要合并的列的操作也需要写完整

代码：

objectSpanMethod({ row, column, rowIndex, columnIndex }){
        if (rowIndex === 2 || rowIndex === 3) {
          let len = Object.keys(row).length
          if(columnIndex === 0){
            return [1, 1];
          }else if(columnIndex === 1){
            return [1, len];
          }else{
              return [0, 0];
          }
        }
      },