Uncaught (in promise) TypeError: t.extends.reduce is not a function

[azazar]

I get TypeError when I use schema with a type definition.

Here's the example: https://is.gd/siIJYX

Uncaught (in promise) TypeError: t.extends.reduce is not a function
    at t.extends (jsoneditor.js:14:76223)
    at jsoneditor.js:14:85375
    at Array.forEach (<anonymous>)
    at t.value (jsoneditor.js:14:85288)
    at jsoneditor.js:14:81837
    at Array.forEach (<anonymous>)
    at t.properties (jsoneditor.js:14:81762)
    at jsoneditor.js:14:87186
    at Array.forEach (<anonymous>)
    at t.value (jsoneditor.js:14:87087)

Schema

{
  "title": "Example",
  "type": "object",
  "definitions": {
    "indexFilter": {
      "type": [
        "string",
        "array",
        "null"
      ],
      "uniqueItems": true,
      "items": {
        "type": "string"
      },
      "format": "table"
    }
  },
  "properties": {
    "filters": {
      "title": "Keyword filters",
      "type": "object",
      "properties": {
        "category": {
          "title": "Categrories",
          "extends": {
            "$ref": "#/definitions/indexFilter"
          }
        }
      }
    }
  },
  "format": "categories"
}