Closing NerdTree buffer prompts message about unsaved changes

[tombruijn]

When closing a NerdTree buffer it will show a prompt about unsaved changes on the latest version of VimR, like issue #571, #516 that appear to have been fixed in older versions, but has broken again since then. I do not see the same problem for help buffers like reported in #530.

I'm currently using version: 0.36.0 (20220102.161018)

Steps to reproduce:

• open VimR with an empty buffer
• Open a NerdTree buffer with :NERDTree
• Close the VimR window using the red quit button in the title bar

Let me know if if you need any more information.