title: Vue router-link param undefined in nested loop
body: <p>I have a loop inside another loop. </p>
  
  <p>The <code>videos.id</code> is undefined in the <code>&lt;router-link&gt;</code> but is rendered just fine otherwise..</p>
  
  <pre><code>    &lt;ul&gt;
        &lt;li v-for="category in categories" :key="category.id"&gt;
         {{category.name}}
          &lt;div v-for="videos in category.videos" :key="videos.id"&gt;
             &lt;router-link v-bind:to="/video-player/ + videos.id"&gt; {{videos.id}}  {{videos.name}}&lt;/router-link&gt;
          &lt;/div&gt;
        &lt;/li&gt;
      &lt;/ul&gt;
  </code></pre>