[Rails 3.2.8] ActiveSupport::BufferedLogger extension, undefined_method

Rails
1

I tried to extend it , with this class , loaded at config time :
config.autoload_paths += Dir["#{config.root}/lib",
“#{config.root}/lib/**/”, “#{config.root}/app/inputs”]

lib/extension.rb
class ActiveSupport::BufferedLogger
def detailed_error(e)
error(e.message)
e.backtrace.each{|line| error line }
end
end

but calling it in my controller

rescue ActiveRecord::RecordInvalid
logger.detailed_error($!)

raises an error => undefined method `detailed_error’ for
#Logger:0x007fb8ecaabcc8
what’s wrong with my class definition ?

thanks for feedback