How to use fallback option

[Wansmer]

Customization of comment processing via fallback, mini.splitjoin and gww:

• If a comment contains text that can be split or joined,
  mini.splitjoin is
  used, which knows how to expose these actions inside the comments;

• If the comment contains nothing that can be processed, the `gww' alignment
  command is used.

-- with lazy.nvim
return {
  'Wansmer/treesj',
  dependencies = { 'nvim-treesitter/nvim-treesitter' },
  config = function()
    local langs = require('treesj.langs').presets

    -- Add fallback to all language
    for _, nodes in pairs(langs) do
      nodes.comment = {
        both = {
          fallback = function(tsn)
            -- mini.splitjoin returns `nil` if nothing to toggle
            local res = require('mini.splitjoin').toggle()

            if not res then
              vim.cmd('normal! gww')
            end
          end,
        },
      }
    end

    require('treesj').setup()
  end,
}

mini.gww.mov

Note that this script is relevant if you are not using a parser for comment.
If you do, you need to configure comment as a separate language.