Oddly enough, if you use the Readonly module to mark your variable readonly, chomping will only fail if the variable is actually tried to be modified:

#!/usr/bin/perl

use strict;
use warnings;

use Readonly;

Readonly my $msg1 => "Hello, world";
Readonly my $msg2 => "Hello, world\n";

chomp $msg1;  # line 11
chomp $msg2;  # line 12

__END__
Modification of a read-only value attempted at /tmp/ro line 12
[download]