libexception-class-perl binary package in Ubuntu Focal amd64

 Exception::Class allows you to declare exceptions in your modules in a
 manner similar to how exceptions are declared in Java.
 .
 It features a simple interface allowing programmers to 'declare'
 exception classes at compile time. It also has a base exception
 class, Exception::Class::Base, that can be used for classes stored in
 files (aka modules ;) ) that are subclasses.
 .
 It is designed to make structured exception handling simpler and
 better by encouraging people to use hierarchies of exceptions in their
 applications.

Source package