big-bang3d doesn't handle mouse wheel scrolling

[co-dan]

Test case:

#lang racket
(require pict3d pict3d/universe)

(big-bang3d 0)

Whenever I scroll the mouse wheel in the canvas I get the following error:

../../../usr/share/racket/collects/racket/private/more-scheme.rkt:148:2: on-key: unknown key code type #f

I believe that the issue is the on-char method defined in private/universe/big-bang.rkt: it calls code->string, which is not able to decode the mouse wheel code (#f for some reason).

I am using Racket v 7.5 on Ubuntu.