Add pretix-widget.js and css to assets initializer

config/initializers/assets.rb

@@ -9,6 +9,6 @@ Rails.application.config.assets.version = '1.0'
 # Precompile additional assets.
 # application.js, application.css, and all non-JS/CSS in app/assets folder are already added.
 Rails.application.config.assets.precompile += [
-  'admin.css', 'admin.js', 'schedule.js', 'public_schedule.css', 'public_schedule_print.css', 'public_schedule.js', 'moment.min.js',
+  'admin.css', 'admin.js', 'schedule.js', 'public_schedule.css', 'public_schedule_print.css', 'public_schedule.js', 'moment.min.js', 'pretix-widget.css', 'pretix-widget.js',
   /\.(?:jpg|png|gif)/ # TODO images in vendor dir?
 ]