Neovim: Use backspace when `buftype=prompt`

prompt-backspace.lua

-- Taken from here:
-- https://github.com/neovim/neovim/issues/14116#issuecomment-977555102
function PromptBackspace()
  -- Have to know the length of the prompt
  local prompt = 2
  local cursor = vim.api.nvim_win_get_cursor(0)
  local line = cursor[1]
  local col = cursor[2]

  if col ~= prompt then
    vim.api.nvim_buf_set_text(0, line - 1, col - 1, line - 1, col, {''})
    vim.api.nvim_win_set_cursor(0, {line, col - 1})
  end
end

vim.api.nvim_buf_set_keymap(
  0,
  'i',
  '<Bs>',
  '<cmd>lua PromptBackspace()<CR>',
  {noremap = true}
)

This also works.

function PromptBackspace()
  -- Have to know the length of the prompt
  local prompt = 2

  local line = vim.fn.getline('.'):len()
  local col = vim.fn.col('.')

  local feedkeys = function(keys)
    vim.api.nvim_feedkeys(
      vim.api.nvim_replace_termcodes(keys, true, true, true),
      'i',
      true
    )
  end

  if col == prompt + 1 then return end

  if col == prompt + 2 then
    vim.cmd([[normal ch]])
    vim.cmd([[startinsert]])
    return
  end

  if col == line + 1 then
    vim.cmd([[normal cl]])
    vim.cmd([[startinsert]])
    feedkeys('<Right>')
    return
  end

  vim.cmd([[normal ch]])
  vim.cmd([[startinsert]])
  feedkeys('<Right>')
end