```ruby
require 'yaml'
require 'jekyll/minibundle/bundle_file'
require 'jekyll/minibundle/development_file_collection'
require 'jekyll/minibundle/environment'

module Jekyll::Minibundle
  class MiniBundleBlock < Liquid::Block
    def initialize(tag_name, type, _tokens)
      super
      @type = type.strip.to_sym
    end

    def render(context)
      site = context.registers[:site]
      config = get_current_config YAML.load(super), site

      file = if Environment.development?
        DevelopmentFileCollection.new config
      else
        BundleFile.new config
      end

      file.static_file! site
      file.markup
    end

    def default_config
      {
        'source_dir'        => '_assets',
        'destination_path'  => 'assets/site',
        'assets'            => [],
        'attributes'        => {}
      }
    end

    private

    def get_current_config(user_config, site)
      default_config.
        merge(user_config).
        merge({ 'type' => @type, 'site_dir' => site.source })
    end
  end
end

Liquid::Template.register_tag('minibundle', Jekyll::Minibundle::MiniBundleBlock)
```

Define default config as a class instance method
user
```ruby
require 'yaml'
require 'jekyll/minibundle/bundle_file'
require 'jekyll/minibundle/development_file_collection'
require 'jekyll/minibundle/environment'

module Jekyll::Minibundle
  class MiniBundleBlock < Liquid::Block
    def initialize(tag_name, type, _tokens)
      super
      @type = type.strip.to_sym
    end

    def render(context)
      site = context.registers[:site]
      config = get_current_config YAML.load(super), site

      file = if Environment.development?
        DevelopmentFileCollection.new config
      else
        BundleFile.new config
      end

      file.static_file! site
      file.markup
    end

    def self.default_config
      {
        'source_dir'        => '_assets',
        'destination_path'  => 'assets/site',
        'assets'            => [],
        'attributes'        => {}
      }
    end

    private

    def get_current_config(user_config, site)
      MiniBundleBlock.default_config.
        merge(user_config).
        merge({ 'type' => @type, 'site_dir' => site.source })
    end
  end
end

Liquid::Template.register_tag('minibundle', Jekyll::Minibundle::MiniBundleBlock)
```
assistant