($die_on_error ? \&CORE::die : \&CORE::warn)->($error);

##</code><code>##

Undefined subroutine &CORE::warn called

##</code><code>##

($die_on_error ? sub { die shift } : sub { warn shift } )->($error);

##</code><code>##

die $error if $die_on_error;
warn $error;