Sub-errors of arrays are nested only one level.

[ademirovic]

In README there is an example how nesting should behave:

{
  "key": "comments",
  "message": "Error validating all comments",
  "messages": null,
  "fullMessages": null,
  "index": null,
  "subErrors": [
    {
      "key": "content",
      "message": "Content is too short",
      "messages": ["is too short"],
      "fullMessages": ["Content is too short"],
      "index": 1,
      "subErrors": null
    }
  ]
}

Change in #5 resulted with subErrors being nested twice when we had an array of maps.
Example:

{
  "key": "comments",
  "message": "Error validating all comments",
  "messages": null,
  "fullMessages": null,
  "index": null,
  "subErrors": [
    {
      "key": "comments",
      "message": "Error validating all comments",
      "messages": null,
      "fullMessages": null,
      "index": null,
      "subErrors": [
        {
          "key": "content",
          "message": "Content is too short",
          "messages": ["is too short"],
          "fullMessages": ["Content is too short"],
          "index": 1,
          "subErrors": null
        }
      ]
    }
    
  ]
}

This change makes nesting behave according to README example.
Tested it also with my project that has several examples of nested arrays, similar to the example in README :)

[space-measurer]

Looks good to me. 👍

[neektza]

@pozhega please 👀 so we can merge