Compiler fail: Stack inconsistency detected in <unknown> at index 40: found 2, expected 0.

(defparameter *abcl1*
  '(lambda (a)
    (declare (optimize (debug 0) (compilation-speed 1)
              (speed 2) (space 3) (safety 1)))
    (ash 0
     (bit #*0100
      (catch 'ct7 a)))))

(defun test1 ()
  (let ((fn (compile nil *abcl1*)))
    (mapcar fn '(0 1 2 3))))

(test1) ==>

; Caught ERROR:
;   Stack inconsistency detected in <unknown> at index 40: found 2,
expected 0.