echarts 多个series时自定义tooltip切换图例legend报错

需求

 bug:当series有两条数据,legend取消一条后hover到echarts中会报错

tooltip:下的错误代码 

    formatter: params => {
            let str = "";
            params.forEach(item => {
              str = `2022-${item.name.padStart(2, 0)}<br/>
                ${params[0].marker}抽检数量（次）：${params[0].value}<br/>
                ${params[1].marker}不合格率：${params[1].value}%<br/>
                  `;
            });
            return str;
          }

以下为正确代码 

   formatter: function(params) {
            let str = `2022-${params[0].name.padStart(2, 0)}<br/>`;
            params.map(item => {
              if (
                item.componentSubType === "bar" ||
                item.componentSubType === "line"
              ) {
                str +=
                  item.componentSubType === "line"
                    ? `${item.marker}${item.seriesName}：${item.value}%<br />`
                    : `${item.marker}${item.seriesName}（次）：${item.value}<br />`;
              }
            });
            return str;
          }