displaying a backtrace in the shell

[Erica L Cooper]

hello,

I am trying to get a guile script that is executed on a port server 
to display a backtrace if there is an error.  as of now I have:

(define (backtrace-test args)
    (catch
        'ignore
      (lambda ()
        (lazy-catch
         #t
         (lambda () (throw 'test-error))
         (lambda (key . args)
           (let ((stack (make-stack #t)))
             (throw 'ignore
               (with-output-to-string
                   (lambda ()
                     (display-backtrace stack (current-output-port)))))))))
      (lambda (k . v)
        (display (car v)))))

which, if you run in interactive Guile, displays the backtrace without 
complaint.  however, when you execute this from the command line, it 
says,

Exception during displaying of backtrace: wrong-type-arg

why is this?  any help is greatly appreciated.

Thanks,
Erica