I can't get this to work :(

[adoreparler]

Operating System: MacOS Ventura 13.4.1 - Apple M2 Max
Vim Version: VIM - Vi IMproved 9.0 (2022 Jun 28, compiled Apr 15 2023 04:26:46)

vimrc:

vnoremap <C-c> :w !pbcopy<CR><CR> 
noremap <C-v> :r !pbpaste<CR><CR>
nnoremap <C-n> :NERDTree<CR>

" Use tab for trigger completion with characters ahead and navigate
" NOTE: There's always complete item selected by default, you may want to enable
" no select by `"suggest.noselect": true` in your configuration file
" NOTE: Use command ':verbose imap <tab>' to make sure tab is not mapped by
" other plugin before putting this into your config
inoremap <silent><expr> <TAB>
      \ coc#pum#visible() ? coc#pum#next(1) :
      \ CheckBackspace() ? "\<Tab>" :
      \ coc#refresh()
inoremap <expr><S-TAB> coc#pum#visible() ? coc#pum#prev(1) : "\<C-h>"

" Make <CR> to accept selected completion item or notify coc.nvim to format
" <C-g>u breaks current undo, please make your own choice
inoremap <silent><expr> <CR> coc#pum#visible() ? coc#pum#confirm()
                              \: "\<C-g>u\<CR>\<c-r>=coc#on_enter()\<CR>"

function! CheckBackspace() abort
  let col = col('.') - 1
  return !col || getline('.')[col - 1]  =~# '\s'
endfunction

call plug#begin()

" Polyglot is Syntax highlighting
Plug 'sheerun/vim-polyglot'

" Code Completion
Plug 'neoclide/coc.nvim', {'branch': 'release'}

" Side Bar
Plug 'preservim/nerdtree'

" ColorScheme
Plug 'NLKNguyen/papercolor-theme'

" Bottom Bar
Plug 'vim-airline/vim-airline'

Plug 'pangloss/vim-javascript'
Plug 'leafgarland/typescript-vim'
Plug 'peitalin/vim-jsx-typescript'
Plug 'styled-components/vim-styled-components', { 'branch': 'main' }

Plug 'OmniSharp/omnisharp-vim'
Plug 'dense-analysis/ale'
Plug 'nickspoons/vim-sharpenup'
Plug 'junegunn/fzf'
Plug 'junegunn/fzf.vim'

Plug 'mattn/emmet-vim'


call plug#end()

set number

set background=dark
colorscheme PaperColor
set mouse=a

command! -nargs=0 Prettier :CocCommand prettier.forceFormatDocument

let g:OmniSharp_server_display_loading = 1
let g:OmniSharp_server_use_net6 = 1
let g:OmniSharp_loglevel = 'debug'

let g:ale_linters = { 'cs': ['OmniSharp'] }

let g:user_emmet_leader_key='<C-Y>'

I've tried without that last line also, along with changing it to C-z and that just closes out vim when I press it.

imap:

See below recording, key presses are at the bottom right:

[skipadu]

I think it might be because your imap shows that you already have something on the Ctrl-Y, from the neoclide/coc.nvim:

i <C-Y> * cc#pum#visible() ? coc#pum#confirm() : "<C-Y>"

And reason why Ctrl-Z closes Vim is that it will suspend the process when you press that, in this case Vim.

You could check some other mapping that is available on your setup, for example Ctrl-g

:verbose imap <C-g>