小bug

Challenge [Access MultiDimensional Arrays With Indexes](https://freecodecamp.cn/challenges/access-multidimensional-arrays-with-indexes#?solution=%2F%2F%20%E5%88%9D%E5%A7%8B%E5%8C%96%E5%8F%98%E9%87%8F%0Avar%20myArray%20%3D%20%5B%5B1%2C2%2C3%5D%2C%20%5B4%2C5%2C6%5D%2C%20%5B7%2C8%2C9%5D%2C%20%5B%5B10%2C11%2C12%5D%2C%2013%2C%2014%5D%5D%3B%0A%0A%2F%2F%20%E8%AF%B7%E5%8F%AA%E4%BF%AE%E6%94%B9%E8%BF%99%E6%9D%A1%E6%B3%A8%E9%87%8A%E4%BB%A5%E4%B8%8B%E7%9A%84%E4%BB%A3%E7%A0%81%0Avar%20myData%20%3D%208%3B%2F%2FmyArray%5B2%5D%5B1%5D%3B%0A%0A) has an issue.
User Agent is: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36.
Please describe how to reproduce this issue, and include links to screenshots if possible.

My code:
```javascript
// 初始化变量
var myArray = [[1,2,3], [4,5,6], [7,8,9], [[10,11,12], 13, 14]];

// 请只修改这条注释以下的代码
var myData = 8;//myArray[2][1];

直接赋值为8也能通过
```