metadata-push-hook: do not crash on new hidden metadata
If we were creating a DM, for which no %groups metadata exists, the
+transform-proxy-update arm would crash, preventing the creation of new
DMs.
=/ role=(unit (unit role-tag))
(role-for-ship:grp group.update src.bowl)
=/ =metadatum:store
- (need (peek-metadatum:met %groups group.update))
+ (fall (peek-metadatum:met %groups group.update) *metadatum:store)
?~ role ~
?^ u.role
?: ?=(?(%admin %moderator) u.u.role)
