Only use prettierd with `formatter.nvim` if a prettier config file is found.

formatter.lua

local ok, formatter = pcall(require, "formatter")
if not ok then
  return
end

local util = require "formatter.util"

local find_git_ancestor = function ()
  local path = util.get_current_buffer_file_path()
  local root = path
  while root ~= "/" do
    local git_dir = root .. "/.git"
    local fd = vim.loop.fs_opendir(git_dir)
    if fd then
      vim.loop.fs_closedir(fd)
      return root
    end
    root = vim.fn.fnamemodify(root, ":h")
  end
end

local prettierd = function()
  local root = find_git_ancestor()
  local possible_filenames = {
    ".prettierrc",
    ".prettierrc.json",
    ".prettierrc.json5",
    ".prettierrc.yaml",
    ".prettierrc.yml",
    ".prettierrc.js",
    ".prettier.config.js",
    ".prettierc.mjs",
    ".prettier.config.mjs",
    ".prettierrc.cjs",
    ".prettier.config.cjs"
  }

  for _, filename in ipairs(possible_filenames) do
    local prettier_config = root .. "/" .. filename
    local fd = vim.loop.fs_open(prettier_config, "r", 438)
    if fd then
      vim.loop.fs_close(fd)
      return {
        exe = "prettierd",
        args = { "--stdin-filepath", vim.api.nvim_buf_get_name(0) },
        stdin = true,
      }
    end
  end

  return nil
end