Fix cannot load `vital.vim` by `on_func = 'vital#vital#'`

[ogaken-1]

Problems summary

I configured vital.vim as lazy with on_func: 'vital#vital#'.

dein.vim doesn't load vital.vim on executing let s:V = vital#vital#new().

Environment

OS: Arch Linux (WSL)

Vim/Neovim version: NVIM v0.9.0-dev-708+ge7ea15660

dein.vim version: ea1a48cf

Minimal configuration

init.vim

const s:here = fnamemodify(expand('<sfile>:p'), ':h')
const s:dein_cache = s:here .. '/dein'
const s:dein_dir = s:dein_cache .. '/repos/github.com/Shougo/dein.vim'

if &rtp !~# '/dein.vim'
  if !isdirectory(s:dein_dir)
    call system(printf('git clone https://github.com/Shougo/dein.vim.git --depth 1 %s', s:dein_dir))
  endif
  execute printf('set rtp^=%s', s:dein_dir)
endif

call dein#begin(s:dein_cache)

call dein#add('vim-jp/vital.vim', #{ lazy: 1, on_func: 'vital#vital#' })

call dein#end()

if dein#check_install()
  call dein#install()
endif

const s:Vital = vital#vital#new()

[Shougo]

Merged.