流量波动趋势echarts category配置项内容和展示

在自己平台画折线图，一条数据时报错

      //趋势图
var getOption = function (chart_name) {
    var option = {
        title : {
            text: chart_name,
            subtext: ''
        },
        tooltip : {
            trigger: 'axis'
        },
        legend: {
            data:[],
            x : 'right',
            padding: 25,
        },         
		toolbox: {
            show : true,
            feature : {
                mark : {show: false},
                dataView : {show: true, readOnly: false},
                magicType : {
                    show: false,
                    type: ['line', 'funnel']
                },
                restore : {show: false},
                saveAsImage : {show: true}
            }
        },
        calculable : false,
        grid : {
                x2 : 35,
                x : 60
            },
        xAxis : [],
        yAxis : [
            {
                type : 'value',
                axisLabel : {
                    formatter: '{value}',
                    show:true
                },
                splitArea : {show : true}
            }
        ],
        series : [],
        animation: false
        }
        return option
    };
var makeGraph = function (option,data, elememtID) {
    var xAxisObj = {
        type : 'category',
        boundaryGap : false
    };
    xAxisObj['data'] = data['date'];
    option['xAxis'].push(xAxisObj); 
    for (var key in data) {
        if (key !== 'date') {
            option['legend']['data'].push(key);
            var seriesObj = {
                type:'line'
            };
            seriesObj['symbol'] = 'none';
            seriesObj['name'] = key;
            seriesObj['data'] = data[key];
            option['series'].push(seriesObj);
        }
    }
    var myChart = echarts.init(document.getElementById(elememtID));
    myChart.setOption(option,true);
};


var flowOption = getOption('流量波动趋势');
data = {"date": ["2017-11-19", "2017-11-20", "2017-11-21", "2017-11-22", "2017-11-23", "2017-11-24", "2017-11-25", "2017-11-26", "2017-11-27"], "c8726b1d": [161992, 36255748, 29286485, 35713193, 30966991, 190651468, 47285742, 188889260, 49193835]};
makeGraph(flowOption, data,'chart-panel');