simple helper vs calss helper reference update which would be fixed by octane

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  arr: [],
  actions: {
    emptyArr() {
      this.set('arr', []);
    },
    
    nonEmptyArr() {
      this.set('arr', [1]);
    },
    
    push(x) {
      this.arr.pushObject(x);
    },
    
    pop() {
      this.arr.popObject();
    }
  }
});

helpers.empty.js

/*import { helper } from '@ember/component/helper';
import { isEmpty } from '@ember/utils';

export default helper(function emptyHelper([obj]) {
  console.log('calling empty heler with:', obj);
  return isEmpty(obj);
});*/

import Helper from '@ember/component/helper';
import { computed, get, observer, set } from '@ember/object';
import { equal } from '@ember/object/computed';

export default Helper.extend({
  object: [],

  /*isEmpty: computed('object.length', function () {
    return get(this, 'object.length') === 0;
  }).readOnly(),*/

  isEmpty: equal('object.length', 0),

  onChange: observer('object.length', function() {
    this.recompute();
  }),

  compute([obj]) {
    set(this, 'object', obj);

    return get(this, 'isEmpty');
  }
});

templates.application.hbs

this.arr is empty: {{empty this.arr}}
<br>
this.arr.length: {{this.arr.length}}
<br>
<br>
<button {{action "push" 1}}>push</button>
<button {{action "pop"}}>pop</button>
<button {{action "nonEmptyArr"}}>new non empty arr</button>
<button {{action "emptyArr"}}>new empty arr</button>
{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}