title: fontawesome error "Could not find one or more icon"
body: <p>I followed <a href="https://fontawesome.com/how-to-use/on-the-web/using-with/vuejs" rel="noreferrer">https://fontawesome.com/how-to-use/on-the-web/using-with/vuejs</a>.</p>
  
  <p>But when use it like:</p>
  
  <pre><code>import { library } from '@fortawesome/fontawesome-svg-core'
  import { faBars } from '@fortawesome/free-solid-svg-icons'
  import { faTwitter, faFacebook, faStackOverflow, faGithub } from '@fortawesome/free-brands-svg-icons'
  import { FontAwesomeIcon } from '@fortawesome/vue-fontawesome'
  
  ...
  
  library.add(faBars, faTwitter, faFacebook, faStackOverflow, faGithub )
  Vue.component('font-awesome-icon', FontAwesomeIcon)
  
  ...
  
  &lt;font-awesome-icon icon="twitter" class="icon alt"/&gt;
  </code></pre>
  
  <p>Got: </p>
  
  <blockquote>
    <p>Could not find one or more icon(s) {prefix: "fas", iconName: "twitter"}</p>
  </blockquote>