title: The method 'setMockMessageHandler' isn't defined for the class 'BasicMessageChannel<dynamic>'
body: <p>After running the Flutter project, I get this error. What can I do to solve it?</p>
  <pre><code>Error: The method 'setMockMessageHandler' 
  isn't defined for the class 'BasicMessageChannel&lt;dynamic&gt;'.
  
  FAILURE: Build failed with an exception.
  </code></pre>