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Neovim version (nvim -v)

NVIM v0.8.1

Operating system/version

MacOS 13.3.1

Describe the bug

Summary:
When Noice is used together with https://github.com/lervag/vimtex, which provides an extensive omnicompletion, an error "Error E5248: Invalid character in group name" appears for each completion candidate.

Buggy behavior:

With the following lazy.nvim spec, the error occurs (see screenshot)

    {
      "folke/noice.nvim",
      opts = {},
    },
    { "MunifTanjim/nui.nvim" },
    { "lervag/vimtex" },

Correct behavior:
Disabling the popupmenu fixes the issue. Removing the opts table entirely also fixes the issue.

    {
      "folke/noice.nvim",
      opts = {
        popupmenu = {
          enabled = false, -- enables the Noice popupmenu UI
          ---@type 'nui'|'cmp'
          backend = "nui", -- backend to use to show regular cmdline completions
          ---@type NoicePopupmenuItemKind|false
          kind_icons = false, -- setting this to `false` by itself does not fix the issue
        },
      },
    },
    { "MunifTanjim/nui.nvim" },
    { "lervag/vimtex" },

Additional context:
I asked in the Gitter and @clason had the following comment: "VimTeX provides word, abbrv, and menu, which noice may not expect".

Steps To Reproduce

1. Use the below repro.lua
2. nvim -u repro.lua repro.tex
3. Type i\<C-x><C-o> (i.e. type a leading \ and enter omnicompletion) to trigger the error.

(Note: a repro.tex file is not provided because this is an empty file on purpose, which was used to generate the above screenshots)

Expected Behavior

See above

Repro

-- DO NOT change the paths and don't remove the colorscheme
local root = vim.fn.fnamemodify("./.repro", ":p")

-- set stdpaths to use .repro
for _, name in ipairs({ "config", "data", "state", "cache" }) do
  vim.env[("XDG_%s_HOME"):format(name:upper())] = root .. "/" .. name
end

-- bootstrap lazy
local lazypath = root .. "/plugins/lazy.nvim"
if not vim.loop.fs_stat(lazypath) then
  vim.fn.system({ "git", "clone", "--filter=blob:none", "https://github.com/folke/lazy.nvim.git", lazypath, })
end
vim.opt.runtimepath:prepend(lazypath)

-- install plugins
local plugins = {
  { "folke/tokyonight.nvim" },
  { "folke/noice.nvim", opts = {} },
  { "MunifTanjim/nui.nvim" },
  { "lervag/vimtex" },
}
require("lazy").setup(plugins, {
  root = root .. "/plugins",
})

vim.cmd.colorscheme("tokyonight")
-- add anything else here