[racket] Is this a bug in contracts?

Is this a bug in contracts?  When I ran the following code the
contract in onion% didn't give me an error, yet the contract is on an
"init sh" but the class doesn't have an "init sh" it has an
"init-field sh".  See the line with the comment ;;;;;THIS LINE SHOULD
USE init-field not init

Thanks,
Harry

#lang racket

(define shish-D%
  (class object% (super-new)
    (abstract only-onions?)))

(define skewer%
  (class shish-D% (super-new)
    (define/override (only-onions?)  #t)))

(define/contract onion%
  (class/c [init (sh (is-a?/c shish-D%))]) ;;;;;THIS LINE SHOULD USE
init-field not init
  (class shish-D% (super-new)
    (init-field sh)
    (define/override (only-onions?)
      (and (send sh only-onions?) #t))))

(send (new onion% [sh (new onion% [sh (new skewer%)])]) only-onions?)