Exceptional plugin and edge?

I'm having a problem getting the 'exceptional' plugin (http://
hg.nullstyle.com/exceptional/) to work under edge. Anytime I add the
'handles AccessDeniedError, :with => :access_denied' to a controller I
get an 'uninitialized constant
DeveloperController::AccessDeniedError.'

Does anybody have any insight into this?

Thanks

Matt