Unlocks and returns the unsigned seal event in a gift-wrap
Throws for the same reason unlockSeal does — see the note there.
If the gift wrap does not yield a usable rumor — including an invalid seal signature, unparseable content, or a rumor whose author does not match its seal
Unlocks and returns the unsigned seal event in a gift-wrap
Throws for the same reason unlockSeal does — see the note there.