如何使用rails 2.1中的ExceptionNotifier插件修复"未处理的视图路径发现"错误？

gem install exception_notification

require 'exception_notification'

ActionMailer::Base.delivery_method = :smtp
ActionMailer::Base.smtp_settings = {
  :address => "smtp.gmail.com",
  :port => 587,
  :domain => "example.com",
  :user_name => "your_email@example.com",
  :password => "your_password",
  :authentication => "plain",
  :enable_starttls_auto => true
}

ExceptionNotifier.exception_recipients = ["your_email@example.com"]
ExceptionNotifier.sender_address = %("Exception Notifier"<exception.notifier@example.com>)
ExceptionNotifier.email_prefix = "[ERROR] "

class ActionController::Base
  include ExceptionNotifiable
end