[racket] Problem on creating graphical exe on Windows

Update :
Just found out that my code contained 1 undefined object :
(new button% [parent panel] [label "Cancel"])

because of which command prompt was opening up.
So I defined it as below & the problem is solved now. :)
(define btn (new button% [parent panel] [label "Cancel"]))

But if some error occurs in run-time, the command prompt still shows up.
Is there a way to 'silently' deal with run-time errors?

Thanks.