fix: error when adding qf entries from telescope / :vim

[Axlefublr]

Truthfully I have no clue why this error happened and what it implies, but defaulting to zero worked and doesn't seem to give me any issues anymore.
I tried removing my change just now to re-get the error, and yet the bug didn't happen again.

[stevearc]

Hmmm...this could only happen if the quickfix rendered a line without the proper separators. I'd like to dig in more and try to find the root cause, because I think this quick fix will be insufficient if that's actually what's going on.

What does your config look like? Are you lazy loading at all? Could you possibly find a consistent repro so I can check it on my machine?

[Axlefublr]

Fairly certain now why it happens, and it comes in tandem with #9

So first, I trigger the #9 bug. I then close the qflist.

I try to fill it again via something like :vim;function; % — blammo, error.

So at least in theory this bug shouldn't be your responsibility either; I'll see if changing up guessindent will fix both issues.

[Axlefublr]

#9 got mostly fixed, but this, turns out, is indeed different, and isn't related to guessindent (I disabled it to test)

Repro:

1. :vim;function; %
2. open qflist
3. close it without doing anything
4. :vim;target; %
5. error happens

...cal/share/nvim/lazy/quicker.nvim/lua/quicker/display.lua:195: attempt to perform arithmetic on local 'offset'
 (a nil value)
stack traceback:
^I...cal/share/nvim/lazy/quicker.nvim/lua/quicker/display.lua:195: in function 'add_item_highlights_from_buf'
^I...cal/share/nvim/lazy/quicker.nvim/lua/quicker/display.lua:270: in function <...cal/share/nvim/lazy/quicker.n
vim/lua/quicker/display.lua:228>
^I[C]: in function 'xpcall'
^I...cal/share/nvim/lazy/quicker.nvim/lua/quicker/display.lua:128: in function <...cal/share/nvim/lazy/quicker.n
vim/lua/quicker/display.lua:116>

[Axlefublr]

This is my plugin configuration:

	{
		'stevearc/quicker.nvim',
		-- lazy = true,
		---@module "quicker"
		---@type quicker.SetupOptions
		opts = {
			keys = {
				{
					'>',
					function() require('quicker').expand({ add_to_existing = true }) end,
					desc = 'Expand quickfix context',
				},
				{
					'<',
					function() require('quicker').collapse() end,
					desc = 'Collapse quickfix context',
				},
			},
		},
	},

I removed lazy = true, but the issue happened in exactly the same way, so it doesn't seem like it was the culprit.
I also did not do either expand or collapse at all, so this issue shouldn't be related to #9.
After this new test, the solution of this PR no longer works. Well, it removes that specific error, but there's a different error after.

[stevearc]

I'm still not able to reproduce the issue. Could you try with a minimal config like the one below

-- save as repro.lua
-- run with nvim -u repro.lua
-- DO NOT change the paths
local root = vim.fn.fnamemodify("./.repro", ":p")

-- set stdpaths to use .repro
for _, name in ipairs({ "config", "data", "state", "runtime", "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",
    "--single-branch",
    "https://github.com/folke/lazy.nvim.git",
    lazypath,
  })
end
vim.opt.runtimepath:prepend(lazypath)

-- install plugins
local plugins = {
  "folke/tokyonight.nvim",
  {
    "stevearc/quicker.nvim",
    ---@module "quicker"
    ---@type quicker.SetupOptions
    opts = {},
  },
}
require("lazy").setup(plugins, {
  root = root .. "/plugins",
})

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

And, if possible, come up with a file you can source to get a repro, something like

vim.cmd("vim ;function; %")
vim.cmd("copen")
vim.defer_fn(function()
  vim.cmd("cclose")
  vim.defer_fn(function()
    vim.cmd("vim ;target; %")
  end, 1000)
end, 1000)

[Axlefublr]

You mention :cclose, but it was never actually obvious to me — I have a mapping for q! that I use to close every possible window, including the qflist one.
So! The repro is the repro.lua you suggested (1 for 1, no changes to it at all)

1. vim;function; %
2. :copen
3. :q!
4. vim;target; %
5. Error happens

Thank you for your patience and good suggestions for how to repro better, I wouldn't arrive at this without you I don't think.
I don't think you can do much about the user doing :q!, I assume you have some events to run on :cclose or the like, and they don't happen with :q!. So I don't expect you to fix it, I'll probably just specialcase my mapping to do :cclose if it's in a qf window.
However I would be very interested to hear any "inside info" about this, and why it works this way. Would probably be a good idea to include in the readme something like:
"you should be using the plugin's toggle() functionality or :cclose to close the qflist, regardless of whether you interacted with it or not; otherwise, you'll get errors"

[stevearc]

Great, I think I've found the root cause and fixed it in a more graceful way. Can you try out the latest version and LMK if you still have the issue?

[Axlefublr]

omg it works!! thank you so much :D