depend on input in array

controllers.application.js

import Ember from 'ember';
import { computed } from '@ember/object';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  people: [
    Ember.Object.create({ name: 'foo', qty: 2 }),
    Ember.Object.create({ name: 'bar', qty: 3})
  ],
  newList: computed('people.@each.name', function() {
    const newArray = [];
    return this.people.map(person => {
      person.set('isError', computed('qty', function() {
        return this.qty > 2
      }));
      return person;
    });
  })
});

templates.application.hbs

{{#each newList as |person|}}
	<div>{{person.name}} {{input value=person.qty}} ({{person.isError}})</div>
{{/each}}

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"
  }
}