Reject lists of different lengths in same ellipsis form

[iitalics]

(define x* '(x y z))
(define e* (list e1 e2))
(template (L e) (let ([,x* ,e*] ...) ,e3))
;; should be:
;; template: all lists must have the same size
;;  first list: '(x y z)
;;  second list: '(....)