Runtime error when calling /authorization_rules

[bvogel]

Running declarative_authorization 0.5.7 on ruby 1.9.3p448 with rails 3.2.13 I get the following stack trace

RuntimeError - Result does not have a type in front: s(s(:lit, :articles), s(:hash, s(:lit, :includes), s(:array, s(:lit, :view_prices), s(:lit, :change_state), s(:lit, :skip_production)))):
  sexp_processor (4.2.1) lib/sexp_processor.rb:239:in `block in process'
  sexp_processor (4.2.1) lib/sexp_processor.rb:340:in `in_context'
  sexp_processor (4.2.1) lib/sexp_processor.rb:194:in `process'
  declarative_authorization (0.5.7) lib/declarative_authorization/development_support/analyzer.rb:161:in `process_iter'
  sexp_processor (4.2.1) lib/sexp_processor.rb:218:in `block (2 levels) in process'
  sexp_processor (4.2.1) lib/sexp_processor.rb:275:in `error_handler'
  sexp_processor (4.2.1) lib/sexp_processor.rb:217:in `block in process'
  sexp_processor (4.2.1) lib/sexp_processor.rb:340:in `in_context'
  sexp_processor (4.2.1) lib/sexp_processor.rb:194:in `process'
  sexp_processor (4.2.1) lib/sexp_processor.rb:236:in `block (2 levels) in process'
  sexp_processor (4.2.1) lib/sexp_processor.rb:275:in `error_handler'
  sexp_processor (4.2.1) lib/sexp_processor.rb:235:in `block in process'
  sexp_processor (4.2.1) lib/sexp_processor.rb:340:in `in_context'
  sexp_processor (4.2.1) lib/sexp_processor.rb:194:in `process'
  declarative_authorization (0.5.7) lib/declarative_authorization/development_support/analyzer.rb:152:in `analyze'
  declarative_authorization (0.5.7) lib/declarative_authorization/development_support/analyzer.rb:29:in `block in analyze'
  declarative_authorization (0.5.7) lib/declarative_authorization/development_support/analyzer.rb:28:in `analyze'
  declarative_authorization (0.5.7) app/helpers/authorization_rules_helper.rb:27:in `policy_analysis_hints'
  declarative_authorization (0.5.7) app/views/authorization_rules/index.html.erb:16:in `___sers_bvogel__rvm_gems_ruby_______p____gems_declarative_authorization_______app_views_authorization_rules_index_html_erb__903524250580251314_70174496351320'

The corresponding part of autorization_rules.rb is this:

privileges do
  privilege :manage do
    includes :create, :new, :edit, :update, :destroy
  end
  privilege :view do
    includes :index, :show
  end
  privilege :manage, :articles, includes: [:view_prices, :change_state, :skip_production]
end

authorization do
...