use strict;
use warnings;
use diagnostics;

my $href = {
    list => undef,
};

my @a = @{$href->{list}}; # fails here
foreach my $i (@a) {
    print "$i\n";
}

##</code><code>##

use strict;
use warnings;
use diagnostics;

my $href = {
    list => undef,
};

foreach my $i (@{$href->{list}}) {
    print "$i\n";
}