collector language's test/exn doesn't work

[robby]

The program below should show a passed test, but it shows a failed one.

#lang planet plai/plai:1:14/collector
(test/exn (car 1) "car")

;; init-allocator : -> void
(define (init-allocator) (void))

;; gc:deref : loc -> heap-value
(define (gc:deref loc) #t)

;; gc:alloc-flat : heap-value -> loc
(define (gc:alloc-flat fv) 0)

;; gc:cons : loc loc -> loc
(define (gc:cons hd tl) 0)

;; gc:first : loc -> loc
(define (gc:first pr-ptr) 0)

;; gc:rest : loc -> loc
(define (gc:rest pr-ptr) 0)

;; gc:flat? : loc -> boolean
(define (gc:flat? loc) #t)

;; gc:cons? : loc -> boolean
(define (gc:cons? loc) #f)

;; gc:set-first! : loc loc -> void
(define (gc:set-first! pr-ptr new)

(error 'set-first! "unsupported"))

;; gc:set-rest! : loc loc -> void
(define (gc:set-rest! pr-ptr new)

(error 'set-rest! "unsuppored"))

[plai]

test/exn is for PLAI's error.

"invalid" is a bit rough of a decision, but that's the option I have