support for floating windows

[laher]

I currently use the standard vim movements <C-w> L / <C-W> R to move a floating window into a split.

It'd be nice if winshift.nvim could support the same movements, but when I try :WinShift left etc or :WinShift then an arrow, I'm seeing the following error:

../winshift.nvim/lua/winshift/lib.lua:458 attempt to index local 'target_leaf' (a nil value)

The line in question is here:

https://github.com/sindrets/winshift.nvim/blob/main/lua/winshift/lib.lua#L458

If I try a :WinShift swap, I get a similar error on line 99, attempt to index local 'a' (a nil value):

https://github.com/sindrets/winshift.nvim/blob/main/lua/winshift/lib.lua#L99

For background, I'm using the goto-preview plugin which presents me with floating windows which I'd like to convert to 'norma' windows. It is a bit unusual, but I figure there may be other use cases for this.