Specification says nickname is optional in documents but it's always there
Example:
https://onionoo.torproject.org/details?search=Unnamed&limit=4&fields=nickname
Specification says:
Relay nickname consisting of 1–19 alphanumerical characters. Omitted if the relay nickname is "Unnamed".
I think I would prefer to fix the specification than to fix the Onionoo behaviour, as it's useful to have only one code path in Relay Search instead of more code paths depending on whether or not the field is present.
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