Try to fix the warning due to setting `org-babel-load-languages'

README.org

@@ -2044,29 +2044,26 @@ list detailing and motivating each listing:
 #+name: lst:set-org-options
 #+begin_src emacs-lisp
 (with-eval-after-load 'org
-  (custom-set-variables
-   `(org-babel-load-languages
-     (delq nil '((C . t)
-                 (calc . t)
-                 ,(when (fboundp 'grapviz-dot-mode) '(dot . t))
-                 (emacs-lisp . t)
-                 (eshell . t)
-                 ,(when (fboundp 'fennel-mode) '(fennel . t))
-                 (fortran . t)
-                 ,(when (fboundp 'gnuplot-mode) '(gnuplot . t))
-                 (js . t)
-                 (latex . t)
-                 (lisp . t)
-                 ,(when (fboundp 'lua-mode) '(lua . t))
-                 ,(when (fboundp 'maxima-mode) '(maxima . t))
-                 (org . t)
-                 (perl . t)
-                 ;; The next two functions are not bound during bootstrap.
-                 ,(when (and (fboundp 'choose-common-python-interpreter)
-                             (fboundp 'choose-common-python-linter))
-                    '(python . t))
-                 (shell . t)))))
   (setopt
+   org-babel-load-languages
+   `((C . t)
+     (calc . t)
+     (dot . ,(fboundp 'grapviz-dot-mode))
+     (emacs-lisp . t)
+     (fortran . t)
+     (gnuplot . ,(fboundp 'gnuplot-mode))
+     (js . t)
+     (latex . t)
+     (lisp . t)
+     (lua . ,(fboundp 'lua-mode))
+     (maxima . ,(fboundp 'maxima-mode))
+     (org . t)
+     (perl . t)
+     ;; The Python setup uses the two functions below.
+     ;; Those functions are not yet bound during bootstrap.
+     (python . ,(and (fboundp 'choose-common-python-interpreter)
+                     (fboundp 'choose-common-python-linter)))
+     (shell . t))
    org-export-backends '(ascii beamer html icalendar latex odt texinfo)
    org-file-apps '((auto-mode . emacs)
                    (directory . emacs)
@@ -4270,7 +4267,8 @@ install and use [[https://gitlab.com/andreyorst/ob-fennel][ob-fennel]] with the
            (ensure-package-installation 'fennel-mode 'quelpa))
   (unless (package-installed-p 'ob-fennel)
     (quelpa '(ob-fennel :repo "andreyorst/ob-fennel" :fetcher gitlab)))
-  (ensure-package-selection 'ob-fennel))
+  (when (ensure-package-selection 'ob-fennel)
+    (org-babel-do-load-languages 'fennel (fboundp 'fennel-mode))))
 #+end_src
 
 #+caption[Fennel example]: