Welcome to the CHICKEN Scheme pasting service

;; Compile with csc -d3 testcase.scm 
;; and then run to see it fail

(module testcase () ;; NOTE: It does *not* fail outside a module!
  (import scheme (chicken base) (chicken foreign))

  (define-external (some_callback ((c-pointer void) blabla)) scheme-object
    #t)

  (define (test-callback)
    ((foreign-safe-lambda* void ()
       "C_return(some_callback(NULL));")))

  (test-callback))