         (goto-char (point-min))
         (while (not (eobp))
           (unless (looking-at "^\\([ad]\\)\\([0-9]+\\) \\([0-9]+\\)")
-            (error "invalid rcs patch or internal error in prettier--apply-rcs-patch"))
+            (error "Invalid rcs patch or internal error in prettier-js--apply-rcs-patch"))
           (forward-line)
           (let ((action (match-string 1))
                 (from (string-to-number (match-string 2)))

           (delete-region (progn (forward-visible-line 0) (point))
                                                  (progn (forward-visible-line arg) (point))))))

(defun prettier--apply-rcs-patch (patch-buffer)
  "Apply an RCS-formatted diff from PATCH-BUFFER to the current buffer."
  (let ((target-buffer (current-buffer))
        ;; Relative offset between buffer line numbers and line numbers


;;; Code:

(defcustom prettier-js--prettier-command "prettier"
  "The 'prettier' command."
  :type 'string
  :group 'prettier)

(defcustom prettier-js--prettier-args '()
  "List of args to send to prettier command."
  :type 'list
  :group 'prettier)

(defcustom prettier-js--prettier-target-mode
  "js-mode"
  "Name of the major mode to be used by 'prettier-before-save'."
  :type 'string
  :group 'prettier)

(defcustom prettier-js--prettier-show-errors 'buffer
    "Where to display prettier error output.
It can either be displayed in its own buffer, in the echo area, or not at all.
Please note that Emacs outputs to the echo area when writing
