Require ErrorNotifier before usage in Rollbar plugin

Author: orien

plugins/rollbar/config/initializers/rollbar.rb

@@ -21,6 +21,7 @@
         "ignored" if Samson::Hooks.fire(:ignore_error, options[:exception].class.name).any?
       end
 
+      require 'samson/error_notifier'
       Rollbar::UserInformer.user_information_placeholder = Samson::ErrorNotifier::USER_INFORMATION_PLACEHOLDER
       Rollbar::UserInformer.user_information = <<~HTML
         <br/><br/>