Unable to add items to the inner list of a nested list (JS error)

[joncarlson]

Description

A JS error is thrown when attempting to add an item to a new inner list of a nested list.

Steps to Reproduce

1. Example reproducing the problem
2. Add a new nested list item
3. A new nested list item is created along with an empty inner list
4. Click the add button under the empty inner list

Expected behavior

Items should be able to be added.

Actual behavior

A JS error is thrown and no items can be added.

The problem is the schema becomes:

{
  "nestedList": [
    [
      "lorem",
      "ipsum"
    ],
    null .   // problem here
  ]
}

It should be:

{
  "nestedList": [
    [
      "lorem",
      "ipsum"
    ],
    [] .   // fixed
  ]
}

Version

1.6.1

[joncarlson]

Fixed in #1335