actions.remove issue in v1.1.0+

[msteward]

React Redux Form version: 1.3.0
Lodash Version: 4.17.2

Steps to reproduce:

1. Create repeating form element and add a few instances (see screenshot below for sample form state structure following this) using actions.push('modelName', initialModelState)

2. Remove one of the items using actions.remove('modelName', index) (http://davidkpiano.github.io/react-redux-form/docs/api/actions.html#actions-remove)
3. Try to remove a second item in the array using the same actions.remove method.

Expected Result:

The items are removed as expected.

Actual Result:

The first item is removed without issue. Subsequent attempts to remove items result in the following error:

Further Info

This breakage for me was introduced in v1.1.0. v1.0.15 does not exhibit this error.
The problems appears to be introduced in line 37-66 of src/reducers/form/change-action-reducer.js

On the first remove that works the value of field on line 38 is an object with the $form attribute:

On the second the remove the value is a basic array:

Nothing else had been done to the form state in between the 2 removes and there are no custom reducers involved.

[davidkpiano]

Really excellent issue description, thanks so much! Looking into this now.