Hide statusline not working with floating windows?

[jedahan]

Environment (please complete the following information):

• OS: macOS

• (Neo)Vim version: NVIM v0.5.0-dev+1048-g69103ff0c

• vim-which-key version: c5322b2

• Have you reproduced with a minimal vimrc: ???

set hidden
set showcmd

let g:mapleader = " "
let g:maplocalleader = " "
set timeoutlen=500

lua<<PLUGINS
vim.cmd [[packadd packer.nvim]]

return require('packer').startup(function()
  use {'wbthomason/packer.nvim', opt = true}
  use {'liuchengxu/vim-which-key'}
end)
PLUGINS

let g:which_key_map =  {}
call which_key#register('<Space>', "g:which_key_map")
nnoremap <silent> <leader> <cmd>WhichKey '<Space>'<cr>

autocmd! FileType which_key
autocmd  FileType which_key set laststatus=0 noshowmode noruler noshowcmd
  \| autocmd BufLeave <buffer> set laststatus=2 showmode ruler showcmd
let g:which_key_disable_default_offset = 1
let g:which_key_use_floating_win = 1

let g:which_key_map.f = { 'name' : '+file' }
let g:which_key_map.f.s = 'save-file'
nnoremap <silent> <leader>fs <cmd>update<cr>

Describe the bug
I tried to hide the statuline using whats in the readme, but there are still two lines - the cursor/statusline, and a line above it from the buffer.

Ideally, the bottom two lines would not be visible.

autocmd! FileType which_key
autocmd  FileType which_key set laststatus=0 noshowmode noruler
  \| autocmd BufLeave <buffer> set laststatus=2 showmode ruler

To Reproduce
Steps to reproduce the behavior:

1. Create the minimal vimrc min.vim:

set nocompatible
set runtimepath^=/path/to/vim-which-key
syntax on
filetype plugin indent on

" Here place the configuration that can cause this issue.

2. Start (neo)vim with command: vim -u min.vim

3. Press ''

4. See error

Expected behavior
explained above?

Screenshots
Shown above?

Additional context
Just whats above