ChromiumWebBrowser can throw NullReferenceException after Dispose()

[jamespearce2006]

If the UI thread is blocked for a portion of time before calling Dispose(), it's possible that race condition occurs with InvokeRenderAsync

The upshot is that InvokeRenderAsync does its invoke after Dispose has already finished. In this case, the FileMappingHandle in InteropBitmapInfo will be set to IntPtr.Zero, and things go bad.

I've fixed this by specifically checking for a null Bitmap, and an empty FileMappingHandle, which fixes the problem for me.

Pull Request #1003

[amaitland]

Closing as #1003 has been merged.

[amaitland]

You'd usually create the issue first then submit the PR, then have the PR auto close the issue.

https://help.github.com/articles/closing-issues-via-commit-messages/