Passing in a double nested array when expected triple nested has weird result

[vkarpov15]

    const Model = new Archetype({
      coordinates: [[['number']]]
    }).compile();

    const coordinates = [[-109, 24], [-108, 25], [-108, 24], [-109, 24]];
    const val = new Model({
      coordinates: coordinates
    });
    console.log(val.coordinates);
    assert.deepEqual(val.coordinates, [coordinates]);