Scribble examples fail to use + correctly

[zyrolasting]

I'm on 8.10 [cs], the latest Debian, and am running my code using racket-mode. I have a #lang scribble/manual document that depends on scribble/examples. I'll start with the error.

; +: contract violation
;   expected: number?
;   given: #f
; Context (plain; to see better errortrace context, re-run with C-u prefix):
;   /home/sage/.racket/share/pkgs/scribble-lib/scribble/racket.rkt:1272:26 loop
;   /home/sage/.racket/share/pkgs/scribble-lib/scribble/racket.rkt:1272:26 loop
;   /home/sage/.racket/share/pkgs/scribble-lib/scribble/racket.rkt:1168:0 do-syntax-ize
;   /home/sage/.racket/share/pkgs/scribble-lib/scribble/racket.rkt:1272:26 loop
;   /home/sage/.racket/share/pkgs/scribble-lib/scribble/racket.rkt:1272:26 loop
[...]

This @-expression from my code that raises the error. Simpler examples do not reproduce, so let's go with this for now. It appears that the (struct term:ksub term (body) #:transparent) instance fails in this exact composition, where term is just (struct term () #:transparent). I'm omitting other structure definitions to keep this at least somewhat brief.

@demo[
(define (ksub-example . xs)
  (with-syntax ([(x ...) xs])
    (term:ksub-parse
     #'(module #%kernel '#%kernel
         (#%module-begin
          (#%require '#%kernel
                     (for-syntax '#%kernel)
                     (prefix : '#%kernel)
                     (for-syntax (prefix : '#%kernel)))
          x ...)))))

(ksub-example '(#%provide (all-from '#%kernel)))
]

I use this demo macro. Let #:eval be hypothetical.

(define-syntax-rule (demo forms ...)
   (examples #:eval (example-evaluator) forms ...))

If you change '(#%provide (all-from '#%kernel))) to #'(#%provide (all-from '#%kernel))), the error goes away. Since scribble-lib/scribble/racket.rkt:1272:26 makes heavy use of syntax-span, I suspect that location information disappears in some nontrivial compositions of quoted code in syntax templates.