Decode a UR with a dcbor codec whose first tag names the UR type, as the
reference's URDecodable::from_ur: the UR's type must be the first tag's
name (a codec's other tags do not name accepted UR types), and the codec
decodes the content wrapped in that tag.
TagUnnamed when the codec has no tag or its first tag
has no name (the reference panics there).
Throws
Custom when the UR's type is not the first tag's
name ("expected UR type , but found ") or that name is not a
UR type ("invalid UR type"), as from_ur returns a dcbor::Error; and
whatever the codec throws for the content.
Decode a UR with a dcbor codec whose first tag names the UR type, as the reference's
URDecodable::from_ur: the UR's type must be the first tag's name (a codec's other tags do not name accepted UR types), and the codec decodes the content wrapped in that tag.