title: Error when loading an image from the assets
body: <p>I am trying to use a PNG file as an icon image.</p>
  
  <p>I have an <code>assets</code> folder in the root of my project.</p>
  
  <p>The file's path is <code>assets/icons/Dumbbell.png</code>.</p>
  
  <p>I loaded my assets in the pubspec file:</p>
  
  <pre><code>flutter:
    uses-material-design: true
    assets:
      - assets/icons/
  </code></pre>
  
  <p>And in a Stateful widget's state I'm trying to use it:</p>
  
  <pre><code> @override
    Widget build(BuildContext context) {
      return Scaffold(
        ...
        bottomNavigationBar: BottomNavigationBar(
          items: const &lt;BottomNavigationBarItem&gt;[
             BottomNavigationBarItem(
              title: Text('Workout'),
              icon: Image.asset(
                'assets/icons/Dumbbell.png',
              ),
            ),
          ],
        ),
      );
    }
  </code></pre>
  
  <p>I just can't make it work!</p>
  
  <p>EDIT: I removed the <code>const</code> keyword and added another <code>BottomNavigationBarItem</code> and now everything is working perfectly!</p>