bug: :Lazy sync <plugin> deletes contents immediately

[T-727]

Did you check docs and existing issues?

• I have read all the lazy.nvim docs
• I have searched the existing issues of lazy.nvim
• I have searched the exsiting issues of plugins related to this issue

Neovim version (nvim -v)

0.8.1

Operating system/version

Windows 11

Describe the bug

Problem

Running:

:Lazy sync <plugin-name>

immediately deletes the plugin's directory contents,
resulting in many unrecoverable errors because lazy tries to read the non-existing contents afterwards.

Proposed solutions

• Read the contents before deleting

Steps To Reproduce

• Open Neovim
• Run :Lazy sync lazy.nvim for example

Expected Behavior

Normal plugin syncing.

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

vim.cmd.colorscheme("tokyonight")
-- add anything else here
vim.api.nvim_create_autocmd("User", {
  pattern = "VeryLazy",
  command = "Lazy sync lazy.nvim",
})