bug: search will broken when null character `^@` in file content

[3Xpl0it3r]

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• [X] I have read all the flash.nvim docs
• [X] I have searched the existing issues of flash.nvim
• [X] I have searched the existing issues of plugins related to this issue

Neovim version (nvim -v)

v0.9.1

Operating system/version

Macos 11.7.6

Describe the bug

when file content like blow then execute search / will trigger panic

Steps To Reproduce

none

Expected Behavior

expected execute search without no error

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

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