If the die message ends in \n then you won't see the file/line information.

If it's code that you don't have control over generating the error, such as in a CPAN module, then you might need to run it in an eval{} block, and modify the error message before re-throwing it.

eval { Some::Module::send_mail() };
if ($@) {
    (my $error = $@) =~ s/ at .* line \d+$//;
    die $error;
}
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