Problem with add-to-list in babel src block

Question

When I execute a babel src block with add-to-list function like this:

#+begin_src emacs-lisp 
(add-to-list 'org-src-lang-modes (quote ("plantuml" . fundamental)))
#+end_src

I will get this error message:

executing Emacs-Lisp code block...
orgtbl-format-line: Wrong type argument: listp, fundamental

The syntax is correct, as I can evaluate it on .emacs buffer without a problem.

The org-mode version is 8.2.10 if it helps.

Answer 1

When evaluating the code, Org-mode takes the return value of add-to-list, which is the list with the new element added, and tries to display it. Lists are displayed as tables, but apparently it doesn't like symbols in the list. (I'm inclined to think that this is a bug in Org-mode.)

You can work around it by asking Org-mode not to display the return value of the code block:

#+BEGIN_SRC emacs-lisp :results silent