Link works for VIM 9.0 but report error for VIM 9.1

[ericsunplus]

Prior to submitting a new issue make sure to complete these steps:

• [√] Include the VimWiki settings from your .vimrc

" Wiki Directories and Settings
let wiki_1 = {}
let wiki_1.path = 'd:/gitlab/mywiki/projDiary/Content'
let wiki_1.path_html = 'd:/gitlab/mywiki/projDiary/Html'
let wiki_1.diary_sort = 'asc'
let wiki_1.nested_syntaxes = {'py': 'python', 'c': 'c', 'bat': 'dosbatch'}
let wiki_1.links_space_char = '_'
let wiki_1.diary_caption_level = -1
let wiki_1.diary_frequency = 'weekly'
let wiki_1.diary_start_week_day = 'wednesday'
let wiki_2 = {}
let wiki_2.path = 'd:/gitlab/mywiki/test/'
let wiki_2.path_html = 'd:/gitlab/mywiki/test_html/'
let wiki_2.diary_sort = 'asc'
let wiki_2.nested_syntaxes = {'py': 'python', 'c': 'c', 'bat': 'dosbatch'}
let wiki_2.diary_frequency = 'weekly'
let wiki_2.diary_start_week_day = 'wednesday'
let g:vimwiki_list = [wiki_1, wiki_2]
let g:vimwiki_conceal_pre = 1
let g:vimwiki_valid_html_tags = 'b,i,s,u,sub,sup,kbd,br,hr,span'
" Don't have menu
let g:vimwiki_menu = ''
" Integrate with Calendar
let g:vimwiki_use_calendar = 1

• [√] Include the syntax you are using (default / Markdown / MediaWiki)
  default

• [√] Provide a detailed description of the problem including steps to reproduce the issue.
  Press Enter on a link works on V9.0 but report the following error on V9.1 vim in windows 10.
  
  Looking through vimwiki\autoload\vimwiki\base.vim it seems s:win32_handler defined inside vimwiki#base#system_open_link is not recognized.

  If I install back the V9.0 VIM version the issue is gone.

• [√] Include the output of :VimwikiShowVersion.