title: How to update only one object with vue.set
body: <p>I have an array with companies like this:</p>
  
  <pre><code>[{
      "id": 1,
      "firstname": "lorem",
      "lastname": "ipsum",
      "name": "something",
      "subscription": "premium",
      "active": 1
  }]
  </code></pre>
  
  <p>The companies are displayed in a layout and when I click on one of them it triggers:</p>
  
  <pre><code>lockCompany(id, index) {
      Vue.set(this.companies, index, {active: 0});
  }
  </code></pre>
  
  <p>But.. when I set active to 0 it removes firstname etc.. Am I doing something wrong?</p>