```ruby
module Middleman
  module Pagination
    class ExtensionContext
      extend Forwardable
      
      def_delegators :app, :sitemap, :index_file, :data

      def initialize(extension)
        @extension = extension
      end
      
      def configuration
        @configuration ||= Configuration.new
      end

      def app
        @extension.app
      end
    end
  end
end```

Fix for uninitialized constant Forwardable
user
```ruby
require 'forwardable'

module Middleman
  module Pagination
    class ExtensionContext
      extend Forwardable
      
      def_delegators :app, :sitemap, :index_file, :data

      def initialize(extension)
        @extension = extension
      end
      
      def configuration
        @configuration ||= Configuration.new
      end

      def app
        @extension.app
      end
    end
  end
end```
assistant