I have a question.
Recently, I've been developing a module called "stepper", and as I
occasionally get some stack traces, they look more or less like this:

        at gnu.mapping.Procedure.apply2(Procedure.java:160)
        at stepper$frame7.lambda33reduce(stepper.scm:10145)
        at stepper$frame7.lambda33reduce(stepper.scm:10108)
        at stepper.reduce$check(stepper.scm:541)

The problem with the second and the third line is that the stepper module
contains some 700 lines, so that the lines 10145 and 10108 don't even exist.

What is the likely reason for this behavior?

(I can help reproduce it if needed - in the sources of GRASP - but I don't
think I'll find time to build a minimal reproducible example)