示例中的Heatmap.js错误

Question

我尝试使用heatmap.js库，在示例代码中，浏览器控制台获取错误 未捕获的TypeError：无法读取属性＆＃39; style＆＃39;为null 在362行 我没有触及示例代码，但它无法正常工作

<div id="heatmapContainerWrapper">
  <div id="heatmapContainer">

  </div>
</div>

<script src="/build/heatmap.js"></script>
<script>
  window.onload = function() {
    // create a heatmap instance
    var heatmap = h337.create({
      container: document.getElementById('heatmapContainer'),
      maxOpacity: .6,
      radius: 50,
      blur: .90,
      // backgroundColor with alpha so you can see through it
      backgroundColor: 'rgba(0, 0, 58, 0.96)'
    });
    var heatmapContainer = document.getElementById('heatmapContainerWrapper');

    heatmapContainer.onmousemove = heatmapContainer.ontouchmove = function(e) {
      // we need preventDefault for the touchmove
      e.preventDefault();
      var x = e.layerX;
      var y = e.layerY;
      if (e.touches) {
        x = e.touches[0].pageX;
        y = e.touches[0].pageY;
      }

      heatmap.addData({ x: x, y: y, value: 1 });

    };

    heatmapContainer.onclick = function(e) {
      var x = e.layerX;
      var y = e.layerY;
      heatmap.addData({ x: x, y: y, value: 1 });
    };

  };
</script>

感谢您的帮助。