Error while using array inside a array and array inside array

[Image 1][1]

Output I get from above command:
[Image 2][2]

If I go more deep and after this command I add [‘UnorderedList’][‘ListItem’] it gives me error.
[1]: https://i.stack.imgur.com/TKSpS.png
[2]: https://i.stack.imgur.com/xh12R.png