title: Unity missing warning when Button has missing OnClick
body: <p>is there a way to get some kind of info or warning, when any Button component has a missing method?</p>
  
  <p>What I mean by that is that when you implement a method for a Button, assign that method in the scene and then e.g. rename the method, the rename won't update the method call in the scene and so it says "&lt; Missing ScriptName.OldMethodName >".</p>
  
  <p>When this happens I'd like to get notified about that - at least when pressing play, or at the very least when deploying the application.</p>