微信 7.0.20 版本进入小程序 Echarts 折线图无法显示，Echarts 区域显示为空白，代码片段和后台错误提示信息如下：

initEchart() {
      let that = this;
      that.data.echartsComponent.init(function (canvas, width, height, dpr) {
        let chart = echarts.init(canvas, null, {
          width: width,
          height: height,
          devicePixelRatio: dpr
        });
        canvas.setChart(chart);
        echart = chart;
        that.triggerEvent('EchartsInited', that.properties.echartData.id);
        return chart;
      });
    },