title: Sequence contains no elements handling
body: <p>My API has a lot of db calls so I need to handle practically every database call with <code>FirstOrDefault</code> or <code>FirstOrDefaultAsync</code>, but is there a way to do it better then</p>
  <pre class="lang-cs prettyprint-override"><code>if (user == null) return NotFound();
  </code></pre>
  <p>every time I want to retrieve User row from database?</p>