Error with paperclip 4.3.0

[cheerfulstoic]

Started GET "/assets/books/82110505-85d9-4adc-83b1-58e5caca66de/edit" for 127.0.0.1 at 2015-08-24 16:09:57 -0300
Processing by AssetsController#edit as HTML
  Parameters: {"model_slug"=>"books", "id"=>"82110505-85d9-4adc-83b1-58e5caca66de"}
Completed 500 Internal Server Error in 44ms

NameError (uninitialized constant Paperclip::Schema::ActiveRecord):
  app/models/asset.rb:10:in `<class:Asset>'
  app/models/asset.rb:2:in `<top (required)>'
  app/models/book.rb:1:in `<top (required)>'
  app/controllers/assets_controller.rb:21:in `model_class'
  app/controllers/assets_controller.rb:14:in `edit'


  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/actionpack-4.2.3/lib/action_dispatch/middleware/templates/rescues/_source.erb (9.9ms)
  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/actionpack-4.2.3/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb (5.1ms)
  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/actionpack-4.2.3/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (1.5ms)
  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/actionpack-4.2.3/lib/action_dispatch/middleware/templates/rescues/diagnostics.html.erb within rescues/layout (83.7ms)
  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/web-console-2.1.3/lib/web_console/templates/_markup.html.erb (0.4ms)
  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/web-console-2.1.3/lib/web_console/templates/style.css.erb within layouts/inlined_string (0.8ms)
  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/web-console-2.1.3/lib/web_console/templates/_inner_console_markup.html.erb within layouts/inlined_string (0.3ms)
  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/web-console-2.1.3/lib/web_console/templates/_prompt_box_markup.html.erb within layouts/inlined_string (0.4ms)
  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/web-console-2.1.3/lib/web_console/templates/console.js.erb within layouts/javascript (56.6ms)
  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/web-console-2.1.3/lib/web_console/templates/main.js.erb within layouts/javascript (0.7ms)
  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/web-console-2.1.3/lib/web_console/templates/error_page.js.erb within layouts/javascript (0.4ms)
  Rendered /Users/brian/.rvm/gems/ruby-2.2.0/gems/web-console-2.1.3/lib/web_console/templates/index.html.erb (139.1ms)