Visual glitch when window is resized with which key open

[gbrlsnchs]

Environment (please complete the following information):

• OS: Void Linux (kernel 5.7)

• Neovim version: 0.5.0 (nightly)

• vim-which-key version: 4e5bd49

• Have you reproduced with a minimal vimrc: yes

Describe the bug
When the vim-which-key floating window is open and you resize the editor window, the editor window goes blank unless a button is pressed. Also, the floating window is not resized accordingly, so sometimes when the screen is back after pressing a button, the floating window is sized wrongly.

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

let mapleader = "\<Space>"
let g:which_key_map =  {
      \ 'b': {
      \   'name': '+buffer',
      \   'n': ['bnext', 'next-buffer'],
      \  }
      \ }
call which_key#register('<Space>', "g:which_key_map")
nnoremap <silent> <Leader> :WhichKey '<Space>'<CR>

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

3. Type Space and resize the editor (Vim) window

4. The buffer is visually clear (nothing is shown) until a button is pressed

Expected behavior
On resize, either the floating window closes and preservers the editor window intact or it resizes accordingly without glitching the editor window.

Additional context
I am using a WM called bspwm, and am simply toggling between monocle view and two panes split vertically.