System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
   in System.Collections.Concurrent.ConcurrentDictionary`2.get_Item(TKey key)
   in Telerik.Windows.Controls.Map.TilesDownloadManager.UpdateTileCache()
   in Telerik.Windows.Controls.Map.TilesDownloadManager.Process()
   in Telerik.Windows.Controls.Map.TilesDownloadManager.DownloaderThread()
   in System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   in System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   in System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   in System.Threading.ThreadHelper.ThreadStart()

System.Collections.Generic.KeyNotFoundException
  in System.Collections.Concurrent.ConcurrentDictionary`2[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].get_Item(System.__Canon)
  in Telerik.Windows.Controls.Map.TilesDownloadManager.RemoveTile(Telerik.Windows.Controls.Map.TileId)
  in Telerik.Windows.Controls.Map.TilesDownloadManager.RemoveL1Cache()
  in System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
  in System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
  in System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
  in System.Threading.ThreadHelper.ThreadStart()