title: How to add a ScrollController in the body of a NestedScrollView
body: <p>I have a page in an app that paginates data from firebase firestore. To paginate the data, I use a scroll controller which fetches the data once the user scrolls to the bottom.</p>
  <p>The problem is that adding the <code>ScrollController()</code> to the <code>NestedScrollView()</code> doesn't work properly.</p>
  <p>Adding it to a <code>ListView.builder()</code> widget in the body of the <code>NestedScrollView()</code> makes the <code>SliverAppBar()</code> pinned even though it's not. I also get the following exception:</p>
  <pre><code>════════ Exception caught by animation library ═════════════════════════════════
  The Scrollbar's ScrollController has no ScrollPosition attached.
  ════════════════════════════════════════════════════════════════════════════════
  </code></pre>
  <p>The scrollbar is the parent of the <code>ListView.builder()</code> that has the <code>ScrollController()</code> attached.</p>