Error detected while processing E121: Undefined variable: s:cpo_save

[kabirz]

Does this bug happen when you install plugin without vim-polyglot?

Describe the bug:
latest update cause neovim startup error everytime on ubuntu 20.04
···
Error detected while processing /home/zhp/.cache/dein/.cache/init.vim/.dein/ftdetect/ftdetect.vim:
line 3606:
E121: Undefined variable: s:cpo_save
E15: Invalid expression: s:cpo_save
line 3607:
E108: No such variable: "s:cpo_save"
Press ENTER or type command to continue
···
To Reproduce:

[cookie-s]

I'm seeing the same error.
I could make steps to reproduce: https://gist.github.com/cookie-s/bfcee76f24e36cd49a66b0ec55f26569

In this environment, the bundled file /root/.cache/dein/.cache/init.vim/.dein/ftdetect/ftdetect.vim is like

"""
""" vim-go https://github.com/fatih/vim-go/blob/master/ftdetect/gofiletype.vim
"""

let s:cpo_save = &cpo
set cpo&vim

let &cpo = s:cpo_save
unlet s:cpo_save

"""
""" vim-polyglot https://github.com/sheerun/vim-polyglot/blob/master/ftdetect/polyglot.vim
"""

if exists("did_load_polyglot")
  finish
endif

let did_load_polyglot = 1

let s:cpo_save = &cpo
set cpo&vim

augroup filetypedetect
  runtime! filetype.vim
  runtime! ftdetect/*.vim
augroup END

let &cpo = s:cpo_save
unlet s:cpo_save

So I think the error flow is

1. vim-go let s:cpo_save = &cpo
2. vim-go unlet s:cpo_save
3. In vim-polyglot, exists("did_load_polyglot") is not 1.
4. vim-polyglot let did_load_polyglot = 1
5. vim-polyglot let s:cpo_save = &cpo " vim-polyglot
6. vim-polyglot runtime! ftdetect/*.vim recursively loads self.
   1. vim-go let s:cpo_save = &cpo
   2. vim-go unlet s:cpo_save
   3. In vim-polyglot, exists("did_load_polyglot") is 1.
   4. vim-polyglot finish
7. vim-polyglot let &cpo = s:cpo_save No such value!

[sheerun]

I guess renaming this variable will help?

[DanielPower]

I'm still experiencing the issue on the latest release.

[DanielPower]

This seems to have been resolved for me in #623