This commit ensures that an error is thrown when a user fails to be
removed from a group instead of silently failing.
This means when using the api you will receive a 400 instead of a 200 if
there is a failure. The remove group endpoint allows the removal of
multiple users, this change means that if you try to delete 10 users,
but 1 of them fails you will receive a 400 instead of 200 even though
the other 9 were removed successfully. Rather than adding a bunch more
complexity I think this is more than adequate for most use cases.
6fb4c333b0