Question on SLoad SSave and NERDTree

I'm new to vim-startify and I like it a lot.
I'm using NERDTree too.
If I save session and NERDTree is open I have trouble on restore session so I find this workaround:
```vim
let g:startify_session_before_save = [
\ 'silent! NERDTreeClose'
\ ]
autocmd SessionLoadpost * NERDTree
```
Now I can save session and restore showing NERDTree without trouble.
Is there a better way?
Can't I save NERDTree inside session by my poor configuration?
Other can save NERDTree inside session without problem?

best regards,
Leonardo

Start by reproducing the SSave and SLoad behavior with NERDTree open, using the workaround shown in the issue as the comparison case. Inspect the session-save and session-load entry points, and consider the work complete only when the NERDTree restore behavior and the supported configuration are clearly established.

Written by the indexing model from the issue text.