Unable to grant admin rights due to error

It looks like this (there are many more groups, but they were clearly created by us and didn’t have any resemblance with the system groups, so I didn’t include them below):

=> [["everyone", 0],
 ["moderators", 2],
 ["admins", 1],
 ["trust_level_0", 10]
 ["trust_level_1", 11],
 ["trust_level_2", 12],
 ["trust_level_3", 13],
 ["trust_level_4", 14],
 ["Staff", 42]]

I notice that there is no group staff, only Staff - if staff always has id 3 then I guess this indicates that somebody removed it and created a new group (id 42).

Is it enough to create staff again or how can I solve this?