title: Flutter : handle File.path null/empty
body: <p>I have <code>File</code> with name _pickedImage.
  I facing problem with handle File.path null , I already handle <code>path</code> null with this code :</p>
  
  <pre><code> if (pickedImage.path == null)
  </code></pre>
  
  <p>Or</p>
  
  <pre><code>if (pickedImage.path.isEmpty)
  </code></pre>
  
  <p>Everytime i press the button , i can't handle File.path <code>null</code> and i get this error.</p>
  
  <pre><code>═══════ Exception caught by gesture ═══════════════════════════════════════════
  The following NoSuchMethodError was thrown while handling a gesture:
  The getter 'path' was called on null.
  Receiver: null
  Tried calling: path
  
  Handler: "onTap"
  Recognizer: TapGestureRecognizer#c9d89
      debugOwner: GestureDetector
      state: possible
      won arena
      finalPosition: Offset(246.8, 613.3)
      finalLocalPosition: Offset(246.8, 23.3)
      button: 1
      sent tap down
  </code></pre>
  
  <p>I'm doing mistake ?</p>