suggestion: refuse to open `:Files` (and other commands) if `'hidden'` is off and window has unsaved changes

[andmis]

Checklist

• [X] I have fzf 0.54.0 or later
• [X] I have searched through the existing issues

Output of :echo system(fzf#exec() .. ' --version')

n/a

OS

• [ ] Linux
• [ ] macOS
• [ ] Windows
• [ ] Etc.

Problem / Steps to reproduce

sometimes i enter :Files, spend some time to find the file i want to open, then press enter, only to be greeted with an error, because i run w/ 'hidden' off and happen to have some unsaved changes.

it would be great for :Files to refuse to open at all in this case.

[junegunn]

Files can open files even in that case when the user presses CTRL-X, CTRL-T, or CTRL-V, so not opening fzf at all is not desirable. If you really must, It is possible to conditionally disable enter key like so.

command! -bang -nargs=? -complete=dir Files
  \ call fzf#vim#files(<q-args>, fzf#vim#with_preview({'options': &modified && !&hidden ? ['--bind=enter:ignore', '--header', 'Enter key disabled'] : []}), <bang>0)

[junegunn]

Let me see whether if it makes sense to make this the default.