my $ref = eval { defined($asset->{related_files}) ? decode_json($asset->{related_files}) : []; };

##</code><code>##

    print "Exists\n"    if exists $hash{$key};
    print "Defined\n"   if defined $hash{$key};
    print "True\n"      if $hash{$key};

##</code><code>##

$ perl -Mstrict -Mwarnings -E 'my $x; eval { my $y = defined $x ? 1 : 0; }; say $@ if $@; say $y;'
Global symbol "$y" requires explicit package name at -e line 1.
Execution of -e aborted due to compilation errors.

$ perl -Mstrict -Mwarnings -E 'my $x; my $y = eval { defined $x ? 1 : 0; }; say $@ if $@; say $y;'
0