Misleading error message (INI - the header is empty)

[x-yuri]

When a header contains Cyrillic letters, it says the header is empty:

use strict;
use warnings;
use utf8;
# my $hdr = 'test';
my $hdr = 'тест';
open my $h, "<", \$hdr or die $!;

$ perl a.pl
Strings with code points over 0xFF may not be mapped into in-memory file handles
Invalid argument at a.pl line 6.

https://github.com/makamaka/Text-CSV/blob/e3b394ea8d59763d1bfe8aa7c1c3a23d24d91c24/lib/Text/CSV_PP.pm#L1087

I'm running perl-5.36.0.