nvim-libmodal/examples/lua/keymaps-supress-exit.lua

local libmodal = require 'libmodal'

-- register key commands and what they do
local fooModeKeymaps =
{
	[''] = 'echom "You cant exit using escape."',
	q = 'let g:fooModeExit = 1'
}

-- tell the mode not to exit automatically
vim.g.fooModeExit = false

-- enter the mode using the keymaps created before
libmodal.mode.enter('FOO', fooModeKeymaps, true)