title: Enum not default to 0 when not defined
body: <p>I have an enum type defined as follows:</p>
  
  <pre><code>public enum OperationTypeEnum : byte
  {
      /// &lt;remarks/&gt;
      @__NONE = 0,
  
      /// &lt;remarks/&gt;
      Sale = 1,
  
      /// &lt;remarks/&gt;
      Auth = 2
  }
  </code></pre>
  
  <p>In my code, I cast an integer like so:</p>
  
  <pre><code>var operationType = (OperationTypeEnum) anotherIntVariable;
  </code></pre>
  
  <p>When anotherIntVariable is something undefined (e.g. 5), I am hoping to get 0 or __NONE back (since 5 is not defined as one of the valid enum values, but I receive 5 instead.</p>
  
  <p>What do I need to change to make undefined enum values to be 0?</p>
  
  <p>Thanks!</p>