Describe the bug
If you set the HTML like this:

<ul>
  <li>One</li>
  <li>
    <ul>
      <li>Two</li>
    </ul>
  </li>
</ul>

You should get this rendered:

instead, we are getting this:

To Reproduce
Steps to reproduce the behaviour:

1. Open the empty demo
2. Switch to HTML mode
3. Copy/Paste the HTML above to it
4. Switch to visual and see the error

Expected behaviour
This list should display properly

Smartphone (please complete the following information):

• Device: iPhone Xx
• OS: iOS 12
• Version 1.6.0