title: Flutter: This requires the 'non-nullable' language feature to be enabled
body: <p>Getting error in <code>MyApp</code> constructor</p>
  <pre><code>const MyApp({Key? key}) : super(key: key);
  </code></pre>
  <blockquote>
  <p>This requires the 'non-nullable' language feature to be enabled.
  Try updating your pubspec.yaml to set the minimum SDK constraint to 2.12.0 or higher, and running 'pub get'.</p>
  </blockquote>
  <p>but sdk is by default set to 2.12.0 already</p>
  <pre><code>sdk: &quot;&gt;=2.12.0 &lt;3.0.0&quot;
  </code></pre>
  <p>This project is created with the latest versions of Flutter and Dart.</p>
  <p>Dart version: <code>2.13.3</code></p>
  <p>Flutter version: <code>2.2.2</code></p>