Fix the problem of the empty prompt color (#23)
Fix the problem of the empty prompt color (#23)

The empty prompt is always shown as the prefix color even if the prefix is off.

Because the empty color attribute (`$empty_highlight`) is not applied at
`$client_prefix` in `highlight()`.

So I have fixed it.
tmux-plugins/tmux-prefix-highlight,erickpintor/tmux-prefix-highlight