bug#63196: Further on this error message

The source seems to be sxpath.scm -- see "yikes" error which triggers when
n is -2 -4 -6 etc. I don't know how to build guile from sources and cannot
debug further.


(define (node-pos n)
  (lambda (nodeset)
    (cond
     ((not (nodeset? nodeset)) '())
     ((null? nodeset) nodeset)
     ((eqv? n 1) (list (car nodeset)))
     ((negative? n) ((node-pos (+ n 1 (length nodeset))) nodeset))
     (else
      (or (positive? n) (error "yikes!"))
      ((node-pos (1- n)) (cdr nodeset))))))