title: Files not sent to server: Illegal invocation at File.remoteFunction
body: <p>I have a function that preprocess a complex object before sending it to server to save some space, so it creates a copy of the object, and got this error on submission (AJAX).</p>
  
  <p>It was working before I decided to create a "clean" copy of the object. 
  Why is this error thrown?</p>