title: SignalR and 500 Errors
body: <p>I've been playing around with SignalR very successfully so far, but I've found a situation where I have not really been able to find any documented reference or solution.</p>
  
  <p>I have a server side function with a class parameter that has a Double property</p>
  
  <pre><code>public bool AddThing(Thing thing)
  {
      // add and notify client
  }
  
  public class Thing {
      public Double Foo { get; set; }
  }
  </code></pre>
  
  <p>The server rightfully returns a 500 error if I send a Thing object with text instead of a number for the property Foo</p>
  
  <pre><code>{"hub":"ThingHub","method":"AddThing","args":[{"Foo":"bar"}],"state":{},"id":1}
  </code></pre>
  
  <p>Since this happens before the SignalR context kicks in, how can deal with the error at the client side? Does the Hub have any special callbacks or properties to check? Is there anything special I need to do to the Hub on the server side?</p>
  
  <p>Thanks!</p>