custom function getting initialized randomly

[Michael Maurer]

Hello,

I wrote the following function to copy the kill-ring to the scratch
buffer, but it only gets initialized sometimes at the start of emacs,
sometimes not. Why?

(defun copy-to-scratch-on-kill
()
"Copy every kill (delete or yank) to *scratch* buffer."
(let
    ((cur-kill-string
      (current-kill 0 t)))
  (when
      (and
       (not
(equal cur-kill-string ""))
       (not
(equal cur-kill-string prev-kill-string))
       (get-buffer "*scratch*"))
    (with-current-buffer "*scratch*"
      (goto-char
       (point-max))
      (insert cur-kill-string "\n")
      (goto-char
       (point-max))))
  (setq prev-kill-string cur-kill-string)))

(add-hook 'post-command-hook #'copy-to-scratch-on-kill)