json-pretty-print-buffer delete the content of a JSON file

[Terencio Agozzino]

Hey,

I'm using GNU Emacs 28.0.50 and when I use the json-pretty-print-buffer function in a JSON file, the content of the file are removed with "Expecting value" as a message.

Example:

My configuration:

(use-package json-mode
  :delight "J "
  :mode "\\.json\\'"
  :hook (before-save . my/json-mode-before-save-hook)
  :preface
  (defun my/json-mode-before-save-hook ()
    (when (eq major-mode 'json-mode)
      (json-pretty-print-buffer)))

  (defun my/json-array-of-numbers-on-one-line (encode array)
    "Prints the arrays of numbers in one line."
    (let* ((json-encoding-pretty-print
            (and json-encoding-pretty-print
                 (not (loop for x across array always (numberp x)))))
           (json-encoding-separator (if json-encoding-pretty-print "," ", ")))
      (funcall encode array)))
  :config (advice-add 'json-encode-array :around #'my/json-array-of-numbers-on-one-line))

Do you have any idea what the problem is?

Thank you for your work.

[taku0]

json-pretty-print-buffer is a function of json.el. Please contact them.
https://github.com/emacs-mirror/emacs/blob/207cd4c23570dc1cb1fdb57a70c67a3be5cefe33/lisp/json.el#L780