bug: incoherent behaviour when filetype is empty

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

Neovim version (nvim -v)

v0.11.0-dev-164+g3a1515bfe

Operating system/version

Linux loric 6.9.3-zen1-1-zen #1 ZEN SMP PREEMPT_DYNAMIC Fri, 31 May 2024 15:14:26 +0000 x86_64 GNU/Linux

Describe the bug

When edgy is configured with a filter but an empty filetype, the window title gets set but the window itself is not controlled by edgy. I noticed this running Overseer.nvim.

As you can see in the screenshot, the 'Overseer runner' window does not follow edgy config (contrary to the other 2), and is not toggled with edgy.

Steps To Reproduce

Install overseer.nvim
Add { ft = "", filter = function(buf, win) return vim.b.overseer_task ~= nil end, title = "Overseer Runner" } to the edgy bottom section
Run :OverseerToggle

Expected Behavior

The window title should be set and the window should be managed by edgy.

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/edgy.nvim",
  'stevearc/overseer.nvim',
  -- add any other plugins here
}
require("lazy").setup(plugins, {
  root = root .. "/plugins",
})

vim.cmd.colorscheme("tokyonight")
-- add anything else here
require('overseer').setup()
require('edgy').setup({    bottom = {
      {
        ft = "toggleterm",
        open = "ToggleTerm",
        size = {
          height = 0.3,
        },
        filter = function(_, win)
          return vim.api.nvim_win_get_config(win).relative == ""
        end,
        pinned = true,
      },
      "Trouble",
      { ft = "qf", title = "QuickFix" },
      { ft = "OverseerList", title = "Overseer List" },
      { title = "Overseer Runner", ft = "", filter = function (buf, win)
        return vim.b.overseer_task ~= nil
      end,
        size = {
          height = 0.3,
        },
      }
    },
})

folke / edgy.nvim