加入合计属性结果不显示的问题

          <el-table
            ref="multipleTable"
            :key="tableKey"
            v-loading="listLoading"
            :data="list"
            stripe
            border
            :height="tableHeight"
            :header-cell-style="tableHeaderColor"
            :show-summary="showSum"    // 关键属性
            :summary-method="getSummaries"  // 关键属性
            style="width: 100%;"
            @selection-change="handleSelectionChange"
            @row-click="btn"
            @select-all="selectAll"
          >
            <el-table-column type="selection" width="45" align="center" />
            <el-table-column prop="signDate" label="签订时间" width="100px" align="center" :resizable="false" />
            <el-table-column prop="conStatus" label="合同状态" width="100px" align="center" :resizable="false" :formatter="conStatusFormat" />
            <el-table-column prop="conNum" label="合同编号" width="120px" align="center" show-overflow-tooltip :resizable="false" />
            <el-table-column prop="conOwner" label="合同归属" width="100px" align="center" :resizable="false" :formatter="owerFormatter" />
            <el-table-column prop="conMoney" label="合同金额(元)" width="100px" align="center" :resizable="false" />
            <el-table-column prop="backMoney" label="已回款金额(元)" width="110px" align="center" :resizable="false" />
            <el-table-column prop="invoiceMoney" label="已开票金额(元)" width="110px" align="center" :resizable="false" />
            <el-table-column prop="conType" label="合同类型" width="80px" align="center" :resizable="false" :formatter="cusTypeFormat" />
          </el-table>
data() {
    return {
      showSum: false
    }
},
  methods: {
    getSummaries(param) {
      const { columns, data } = param
      if (data !== null) {
        const sums = []
        columns.forEach((column, index) => {
          if (index === 1) {
            sums[index] = '合计:'
            return
          }
          if (column.property === 'conMoney' || column.property === 'backMoney' || column.property === 'invoiceMoney') {
            const values = data.map(item => Number(item[column.property]))
            if (!values.every(value => isNaN(value))) {
              sums[index] = values.reduce((prev, curr) => {
                const value = Number(curr)
                if (!isNaN(value)) {
                  return prev + curr
                } else {
                  return prev
                }
              }, 0)
              sums[index] += ' 元'
            }
          } else {
            sums[index] = ''
          }
        })
        return sums
      }
    },
//查询方法
    // 列表分页方法
    getList() {
      this.listLoading = true
      pageList(
        this.listQuery.page,
        this.listQuery.limit,
        this.listQuery.conNum,
        this.listQuery.conName,
        this.listQuery.conType,
        this.listQuery.conStatus,
        this.listQuery.customerId,
        this.listQuery.checkStatus,
        this.listQuery.conOwner
      ).then(response => {
        this.list = response.data.records
        this.total = response.data.total
        this.showSum = false    //关键信息 加载问题导致不显示,控制其加载后显示
        this.$nextTick().then(() => {   //关键信息
          this.showSum = true   //关键信息
        })
        setTimeout(() => {
          this.listLoading = false
        }, 0.5 * 1000)
      }).catch(error => {
        this.listLoading = false
        this.$messageOK('error', error)
      })
    },
}