hi snvzz, which server did you try it on? i tried few ipv6 servers and it was ok.
Try any DNS name which only has a AAAA record, e.g. ipv6.google.com, which results in “An unexpected error occurred.”
Alright, thanks!
As an added note, your server seems to resolve some A record, despite no A records in the domain.
I suspect whatever you're using for DNS does park all NXDOMAIN into some website of their own.