折线图堆叠，绘图显示bugecharts 折线配置项内容和展示

series：[{data:[120,0]}, {data:[0,20]}] 绘图出现bug

      option = {
    title: {
        text: '折线图堆叠'
    },
    tooltip: {
        trigger: 'axis'
    },
    legend: {
        data:['邮件营销','联盟广告']
    },
    grid: {
        left: '3%',
        right: '4%',
        bottom: '3%',
        containLabel: true
    },
    toolbox: {
        feature: {
            saveAsImage: {}
        }
    },
    xAxis: {
        type: 'category',
        boundaryGap: false,
        data: ['周一','周二']
    },
    yAxis: {
        type: 'value'
    },
    series: [
        {
            name:'邮件营销',
            type:'line',
            stack: '总量',
            data:[120, 0]
        },
        {
            name:'联盟广告',
            type:'line',
            stack: '总量',
            data:[0, 20]
        }
    ]
};