Never nuke a NERDTree using Q

vim/plugin/settings/yadr-window-killer.vim

@@ -4,6 +4,12 @@
 function! CloseWindowOrKillBuffer()
   let number_of_windows_to_this_buffer = len(filter(range(1, winnr('$')), "winbufnr(v:val) == bufnr('%')"))
 
+  " We should never bdelete a nerd tree
+  if matchstr(expand("%"), 'NERD') == 'NERD'
+    wincmd c
+    return
+  endif
+
   if number_of_windows_to_this_buffer > 1
     wincmd c
   else