Babel错误:repl:我们发现了一个不是NodePath实例的路径.Possiblly由于序列化不良

Question

当通过在线Babel转发器运行代码片段(取自关于ES2015中关键字的MDN页面let)时,它失败并出现以下错误:

repl: We found a path that isn't a NodePath instance. Possiblly due to bad serialisation.

码

var list = document.getElementById("list");

for (var i = 1; i <= 5; i++) {
  var item = document.createElement("LI");
  item.appendChild(document.createTextNode("Item " + i));

  let j = i;
  item.onclick = function (ev) {
    console.log("Item " + j + " is clicked.");
  };
  list.appendChild(item);
}

为什么会抛出错误,我该怎么办？