bug: auto load cwd with auto save will save blank session first

[josh-nz]

Relates to #55

If configured with autosave.cwd = true and autoload.cwd = true, when starting Neovim M.load in session.lua will try to autosave. It looks like this should be skipped but for whatever reason, autosave_skip() is returning true for me.

This has the follow behaviour:

1. The cwd json file is parsed first, so session data is in memory.
2. The cwd session is loaded, triggering autosave
3. autosave saves the blank Neovim buffers into the cwd session file
4. session is loaded from data in memory.

While this works, if you have other autosave settings turned off (or Neovim crashes etc), then there is a chance the session will be lost.

Ideally, we skip saving when autoloading from cwd. It looks like this was the intent, and autosave_skip() has a bug. I don't know the nuance of Neovim that the skip function is trying to achieve, but results from my tests are below:

local function autosave_skip()
    -- Skip scratch buffer e.g. startscreen
    local unscratch_buffers = vim.tbl_filter(function(buf)
        return 'nofile' ~= vim.bo[buf].buftype
    end, vim.api.nvim_list_bufs())
    -- unscratch_buffers is true
    -- next(unscratch_buffers) is true
    -- so return evaluates to false
    return not unscratch_buffers or not next(unscratch_buffers)
end

[jedrzejboczar]

Fixed in #55