title: Problem with Ionic back button component not being resolved by Vue
body: <p>I cannot achieve to find out why I'm getting this warning from Vue, and the back button is not working:</p>
  <pre><code>runtime-core.esm-bundler.js?5c40:38 [Vue warn]: Failed to resolve component: ion-back-button 
    at &lt;TheHeader titulo=&quot;Home&quot; &gt; 
    at &lt;IonPage isInOutlet=true registerIonPage=fn&lt;registerIonPage&gt; &gt; 
    at &lt;Home ref=Ref&lt; undefined &gt; key=&quot;/home&quot; isInOutlet=true  ... &gt; 
    at &lt;IonRouterOutlet&gt; 
    at &lt;IonApp&gt; 
    at &lt;App&gt;
  </code></pre>
  <p>It's a simple app from scratch with some pages sharing a header, which I'm trying to outsource in a new component called TheHeader. Since then, the back button no longer works.</p>
  <p>I'm trying to skip unnecessary code to get to the point quicker.
  This is one of my pages, <strong>Home.vue</strong>:</p>
  <pre class="lang-html prettyprint-override"><code>&lt;template&gt;
      &lt;ion-page&gt;
          &lt;the-header titulo=&quot;Home&quot;&gt;&lt;/the-header&gt;
          &lt;ion-content&gt;
          &lt;/ion-content&gt;
      &lt;/ion-page&gt;
  &lt;/template&gt;
  
  &lt;script&gt;
  import { IonContent, IonPage } from '@ionic/vue';
  import TheHeader from '../components/TheHeader.vue';
  
  export default {
    name: 'Home',
    components: {
      IonContent,
      IonPage,
      'the-header': TheHeader
    }
  };
  &lt;/script&gt;
  </code></pre>
  <p>This is my <strong>TheHeader.vue</strong> component:</p>
  <pre class="lang-html prettyprint-override"><code>&lt;template&gt;
      &lt;ion-header&gt;
          &lt;ion-toolbar&gt;
              &lt;ion-buttons name=&quot;start&quot;&gt;
                  &lt;ion-back-button&gt;
                  &lt;/ion-back-button&gt;
              &lt;/ion-buttons&gt;
              &lt;ion-title&gt;
                  {{ titulo }}
              &lt;/ion-title&gt;
          &lt;/ion-toolbar&gt;
      &lt;/ion-header&gt;
  &lt;/template&gt;
  
  &lt;script&gt;
  import { IonHeader, IonToolbar, IonTitle, IonButtons, IonBackButton } from '@ionic/vue'
  
  export default {
      props: [
          'titulo'
      ],
      components: [
          IonHeader, IonToolbar, IonTitle, IonButtons, IonBackButton
      ]
  }
  &lt;/script&gt;
  </code></pre>
  <p>Well, if I navigate from Home to another page, which is basically similar (I'm using a very basic nav menu within ion-content), or even if I reload this page, so no navigation at all, I get the above warning, and in case I navigate to another page, and then I click on the back button, the previous page is not loaded.</p>
  <p>What am I doing wrong?</p>