MAPCAR of DESTRUCTURING-BIND in DEFUN throws error evaluating the defun

[nigel-me]

Found this when destructuring some data.

Corman Lisp gives error (when SBCL doesn't) when mapcar and destructuring-bind are used together in a defun
but fine to have 1) destructuring-bind in defun
and 2) destructuring-bind in mapcar
and 3) putting destructuring-bind in a helper function that mapcar calls in defun works
but both in defun doesn't:

(defparameter data '((a (b c d) . e) (1 (2 3 4) . 5)))
DATA

(defun extract-scale-scores (mydata)
"Extract scale names and their floating-point scores from the given data."
(destructuring-bind (a (&rest b) . c) mydata (cons a c)))
;;; Warning: Unused variable B in function EXTRACT-SCALE-SCORES
EXTRACT-SCALE-SCORES
(extract-scale-scores (first data))
(A . E)
(mapcar #'(lambda (zz) (destructuring-bind (a (&rest b) . c) zz (cons a c))) data)
;;; Warning: Unused variable B in anonymous function
((A . E) (1 . 5))
(defun extract-it (mystuff) (mapcar #'(lambda (zz) (destructuring-bind (a (&rest b) . c) zz (cons a c))) mystuff))
;;; An error of type TYPE-ERROR was detected in function SIGNAL-TYPE-ERROR:
;;; Error: Type error: datum = C, expected type = LIST
;;; Entering Corman Lisp debug loop.
;;; Use :C followed by an option to exit. Type :HELP for help.
;;; Restart options:
;;; 1 Abort to top level.
:C 1

;;; Returning to top level loop.
(defun extract-it (mystuff) (mapcar #'extract-scale-scores mystuff))
EXTRACT-IT
data
((A (B C D) . E) (1 (2 3 4) . 5))
(extract-it data)
((A . E) (1 . 5))

combined defun, mapcar, destructuring-bind works in SBCL (portacle):
CL-USER> (defun extract-it (mystuff) (mapcar #'(lambda (zz) (destructuring-bind (a (&rest b) . c) zz (cons a c))) mystuff))
; in: DEFUN EXTRACT-IT
; (DESTRUCTURING-BIND (A (&REST B) . C) ZZ (CONS A C))
; --> SB-INT:BINDING*
; ==>
; (LET* ((#:G8 (SB-C::CHECK-DS-LIST/&REST ZZ 2 2 '(A # . C)))
; (A (POP #:G8))
; (#:G9 (POP #:G8))
; (B #:G9)
; (C #:G8))
; (CONS A C))
;
; caught STYLE-WARNING:
; The variable B is defined but never used.
;
; compilation unit finished
; caught 1 STYLE-WARNING condition
EXTRACT-IT
CL-USER> (defparameter data '((a (b c d) . e) (1 (2 3 4) . 5)))
DATA
CL-USER> data
((A (B C D) . E) (1 (2 3 4) . 5))
CL-USER> (extract-it data)
((A . E) (1 . 5))
CL-USER>

Also works in CLISP like SBCL

PS editor sees ear-muffs as markup in DEFPARAMETER etc.