class Rails::Application::Configuration

def expand_and_check(extension_list) #:nodoc
  missing_extensions = extension_list - [:all] - available_extensions
  raise LoadError, "These configured extensions have not been found: #{missing_extensions.to_sentence}" if missing_extensions.any?
  if m = extension_list.index(:all)
    extension_list[m] = available_extensions - extension_list
  end
  extension_list.flatten
end