test program to raise error

test.rkt

#lang racket/base
(require racket/gui/base
         racket/class)

(define (do-the-build)
  (define f (new frame% [label "Building..."]))
  (define t (new text% [auto-wrap #t]))
  (define c (new editor-canvas% [parent f] [editor t]))
  (send f show #t)
  (void (thread (lambda ()
                  (parameterize ([current-output-port (open-output-text-editor t)])
                    (thread (lambda ()
                              (printf "Writing program #<path:/gpfs/main/home/dyoo/work/whalesong/examples/eli-number-puzzle/eli-number-puzzle.js>
Skipping writing resource #<path:/gpfs/main/home/dyoo/work/whalesong/examples/eli-number-puzzle/excanvas.js>; already exists
Skipping writing resource #<path:/gpfs/main/home/dyoo/work/whalesong/examples/eli-number-puzzle/canvas.text.js>; already exists
Skipping writing resource #<path:/gpfs/main/home/dyoo/work/whalesong/examples/eli-number-puzzle/optimer-normal-normal.js>; already exists
Writing html #<path:/gpfs/main/home/dyoo/work/whalesong/examples/eli-number-puzzle/eli-number-puzzle.html>
Writing manifest #<path:/gpfs/main/home/dyoo/work/whalesong/examples/eli-number-puzzle/eli-number-puzzle.appcache>
Build complete."))))))))

(define f (new frame% [label "test"]))
(new button% [parent f]
     [label "build!"]
     [callback (lambda (button event) (do-the-build))])

(send f show #t)