title: Ninject - Binding.GetProvider throws NullReferenceException
body: <p>I'm using version 2.2.0.0 of Ninject in a asp.net web forms application and after a few hundred requests, it sometimes throws a NullReferenceException in the GetProvider method of the Binding class.</p>
  
  <p>Example stack trace: <a href="http://pastebin.com/BbhsPQMT" rel="noreferrer">http://pastebin.com/BbhsPQMT</a></p>
  
  <p>The exception only occurs when I stress test the application and the origin of the exception is usually different (resolving distinct interfaces).</p>
  
  <p>In order to try to understand why this issue was ocurring I looked at the Ninject source code and inserted some lines of code for debugging purposes. I later confirmed that the object that is null is the ProviderCallback property in the Binding class.</p>
  
  <p>I also put some code in the set operator of the ProviderCallback property in order to understand if it was being set to null. After running some tests and looking at some memory dumps it seems that the ProviderCallback property is not being set to a null value and so I think the instance being collected by GC.</p>
  
  <p>I still do not understand why this is happening...</p>
  
  <p>Any help is greatly appreciated.</p>
  
  <p><strong>Edit:</strong> We upgraded to the latest version of Ninject just to check if the exception still occurs but we got the same exception after stress testing the application: <a href="http://pastebin.com/YaiaZndz" rel="noreferrer">http://pastebin.com/YaiaZndz</a></p>