Binary package “libmoosex-undeftolerant-perl” in ubuntu eoan

makes Moose attribute(s) tolerant to undef initialization

 Loading MooseX::UndefTolerant in your Moose class
 makes initialization of your attributes tolerant of undef.
 If you specify the value of undef to any of the attributes
 they will not be initialized,
 effectively behaving as if you had not provided a value at all.