False report on embedded arrays comparing

[flight9]

Please test this:

const jsondiffpatch = require('jsondiffpatch').create();
var obj1 = {
    'test': {
        'list': [
          [
            "5b51b577ed668594b0091b56",
            "5b51fc4f695227a5977b716c"
          ],
          0,
          0
        ]
    }
};

var obj2 = {
    'test': {
        'list': [
          [
            "5b51b577ed668594b0091b56",
            "5b51fc4f695227a5977b716c"
          ],
          0,
          0
        ]
    }
};
var delta = jsondiffpatch.diff(obj1, obj2);
console.log('Array delta', JSON.stringify(delta,null,2));

I expect the delta will be undefined(because literally they are equal), but it gives:

Array delta {
  "test": {
    "list": {
      "0": [
        [
          "5b51b577ed668594b0091b56",
          "5b51fc4f695227a5977b716c"
        ]
      ],
      "_t": "a",
      "_0": [
        [
          "5b51b577ed668594b0091b56",
          "5b51fc4f695227a5977b716c"
        ],
        0,
        0
      ]
    }
  }
}

It seems [..., 0, 0] of obj2 are ignored in comparing. Not knowing why.