Fix :type of recently introduced defcustom

* lisp/mb-depth.el (minibuffer-depth-indicator-function): The option
can be nil, so add nil as a choice.  (Bug#47252)

diff --git a/lisp/mb-depth.el b/lisp/mb-depth.el
index f79b0f354e2f443ee16e52f13c50b75c5160ff0b..3cba6a41f2fcc36a914f0dc76b591dc6a25296fc 100644 (file)
--- a/lisp/mb-depth.el
+++ b/lisp/mb-depth.el
@@ -35,7 +35,8 @@
 It is called with one argument, the minibuffer depth,
 and must return a string."
   :version "28.1"
-  :type 'function
+  :type '(choice (const :tag "Default" nil)
+                 (function))
   :group 'minibuffer)
 
 (defface minibuffer-depth-indicator '((t :inherit highlight))