it depends how you want undef ne undef to act.

That's a conceptual question only you can answer, and Perl is right to complain about that.

my advice is to define an extra function adjustable to exactly to the behavior you need

• either like the neqq() hippo mentioned
• or even better cont_links() so you can do join '', map cont_links($_), @{ $general->{ "111111" } };

The complicated logic inside the map merits an dedicated function (plus documentation)