Add some `:safe' keywords

* lisp/org-src.el (org-edit-src-content-indentation):
* lisp/org.el (org-adapt-indentation): Add :safe keyword.

lisp/org-src.el

@@ -128,7 +128,8 @@ editing it with `\\[org-edit-src-code]'.
 
 It has no effect if `org-src-preserve-indentation' is non-nil."
   :group 'org-edit-structure
-  :type 'integer)
+  :type 'integer
+  :safe #'wholenump)
 
 (defcustom org-edit-src-persistent-message t
   "Non-nil means show persistent exit help message while editing src examples.

lisp/org.el

@@ -1474,11 +1474,12 @@ stars).  The following issues are influenced by this variable:
   a headline will be indented when this variable is set.
 
 Note that this is all about true indentation, by adding and
-removing space characters.  See also `org-indent.el' which does
+removing space characters.  See also \"org-indent.el\" which does
 level-dependent indentation in a virtual way, i.e. at display
 time in Emacs."
   :group 'org-edit-structure
-  :type 'boolean)
+  :type 'boolean
+  :safe #'booleanp)
 
 (defcustom org-special-ctrl-a/e nil
   "Non-nil means `C-a' and `C-e' behave specially in headlines and items.