tmate crashes when using terminal mode and catppuccin

### Description

using `tmate` (just tmate, using tmux works fine), open nvim and run `:terminal` then go in to insert mode. tmate will crash

### Neovim version

```markdown
NVIM v0.11.3
Build type: RelWithDebInfo
LuaJIT 2.1.1741730670
```

### Terminal and multiplexer

tmate

### Catppuccin version / branch / rev

catppuccin main

### Steps to reproduce

if you checkout catppuccin `2990ca95788246d693c43b4b2847eae6f2def6b4` it will work. `548b2a2` is the first breaking commit.

verified that the true color and italic support in the bug template are correct inside tmate

i fixed this for my config by adding this to my catppuccin setup:
```lua
highlight_overrides = {
all = function(colors)
return {
TermCursor = { fg = "NONE", bg = "NONE" },
TermCursorNC = { fg = "NONE", bg = "NONE" },
}
end,
},
```

### Expected behavior

latest catppuccin should not crash tmate

### Actual behavior

it crashes not just nvim, but tmate too

### Repro

```Lua
-- tested this repro.lua without making changes and the bug is reproducable

-- 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 = {
"catppuccin/nvim",
-- add any other plugins here
}
require("lazy").setup(plugins, {
root = root .. "/plugins",
})

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

Start by running the supplied Lua reproduction with tmate, Neovim's :terminal, and insert mode, then compare catppuccin commits 2990ca95788246d693c43b4b2847eae6f2def6b4 and 548b2a2. Inspect the changes affecting the TermCursor and TermCursorNC highlights; done means the latest catppuccin no longer crashes Neovim or tmate in this scenario.

Written by the indexing model from the issue text.