[racket] help on error: module-path-index-resolve: "self" index has no resolution?

I'm trying to reuse the definitions of ASL for Moby/js-vm, and ran
across a strange macro error.  I've reduced a test case to show the
bug:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; when.rkt
#lang racket
(define-syntax -when
  ((lambda (dont-care)
     (lambda (stx)
       (syntax-case stx ()
         [(_ q expr ...)
          (syntax/loc stx
            (when q expr ...))])))
   42))

(provide (rename-out [-when when]))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; test-when.rkt
(when 42
  'huh)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

When I try to run test-when.rkt, I see the following error:

    module-path-index-resolve: "self" index has no resolution:
#<module-path-index>

As far as I can tell, the bug is being triggered by the use of the
function application to create when "when" value binding.  Does anyone
know what's happening here?