Subtle mutable data bug

components.child-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  actions: {
    clearPersonData() {
      this.set('person', null)
    }
  }
});

components.parent-component.js

import Ember from 'ember';

class Person {
  constructor(name, age, job) {
    this.name = name
    this.age = age
    this.job = job
  }
}

export default Ember.Component.extend({
  name: Ember.computed('person.name', function () {
    return this.get('person.name') || 'Oops we deleted the person'
  }),
  init() {
    this._super(...arguments)
    this.set('person', new Person('Bob', 50, 'CEO'))
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{parent-component}}
<br>
<br>

templates.components.child-component.hbs

<div style="border: 1px solid; margin: 5px;">
{{#if person}}
  {{person.name}} is {{person.age}} years old and works as a {{person.job}}
  <br><br>
  <button {{action "clearPersonData"}}>Remove details</button>
{{else}}
  We are hiding the person data
{{/if}}
</div>

templates.components.parent-component.hbs

<div style="border: 1px solid; margin: 5px;">
Below might be more data about {{name}}
<br><br>
{{child-component person=person}}
</div>

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"
  }
}