On 28.02.2024 12:54, Ihor Radchenko wrote:
> gerard.vermeulen@posteo.net writes:
> 
>>> You may wrap `org-indent-block' into `condition-case' to catch
>>> user-errors.
>> 
>> The caveat is not a real constraint, since Org has limited support for
>> source block editing in an Org mode buffer when an
>> `org-babel-edit-prep:<LANG>' function signals an user-error.
>> 
>> I show that in the attached no-user-errors-in-edit-prep.org.
> 
> I studied the existing Org handling of various errors related to src
> edit buffers and it seems that we tend to ignore them in a number of
> scenarios. In particular, when major mode fails to load for any reason,
> Org mode does not even throw an error, but simply displays a warning.
> 
> So, I think that we can similarly ignore errors in edit-prep function,
> demoting them to messages.
> 
> (In addition, it does not look like electric-indent-mode triggered in
> your example file by pressing <RET> handles errors gracefully either -
> yet another reason not to throw errors in `org-indent-*' functions)
> 
> Does it make sense?

Your reply helped me to read the Org Babel code from a different view
point.  I re-discovered that `org-babel-edit-prep:sql' handles all
issues gracefully while trying the block below:
#+begin_src sql :engine wrong
a
b
#+end_src
That includes `org-babel-demarcate-block' splitting with the patch.

I do not understand why it works and why I never see the user-error
re-signalled by `org-babel-edit-prep:sql' (even as demoted message).

After writing `org-babel-edit-prep:python' like:
#+begin_src emacs-lisp -n :results silent
(defun harm-full-edit-prep (_info)
   (user-error "Harm-FULL edit-prep"))

(defun org-babel-edit-prep:python (info)
   "Imitate `org-babel-edit-prep:sql'."
   (condition-case nil
       (harm-full-edit-prep info)
     (user-error "Why is this harm-LESS in `org-babel-edit-prep:sql'?")))
#+end_src
and trying it on the block below:
#+begin_src python -i -n :results silent
11
22
#+end_src
I see that this `org-babel-edit-prep:python' handles all issues like
`org-babel-edit-prep:sql' (and it does not matter whether
`electric-indent-mode' is disabled or enabled).

I conclude (contrary to the previous commit message in the patch):

In case functions called by an `org-babel-edit-prep:<LANG>' function
raise an user-error, this `org-babel-edit-prep:<LANG>' function should
re-signal the user-error like `org-babel-edit-prep:sql' does.

Attached you'll find the patch with an updated commit message.

Regards -- Gerard