Re: bug: Error handling in source blocks.

[Berry, Charles]

> On Aug 9, 2021, at 9:13 PM, James Powell <powellj@pdx.edu> wrote:
> 
>  Error handling is important and hard to get right.  Me, I prefer to
>   treat every warning as an error (-Werror in gcc, "options(warn=2)" in
>   R, etc).  I want the system to grind to a halt at the least sign of
>   trouble.

If the effect of an error is to return no result (as in your example), you can 
use a :post header-arg to check for a nil value in `*this*' and issue a 
user-error. 

Example:

#+name: check-res
#+begin_src emacs-lisp
(or *this* (error "nil result")) 
#+end_src


#+begin_src R :exports both :post check-res()
  x <- fffff838293483$x8483848
#+end_src


See (info "(org) Results of Evaluation") and scroll to `post-processing' for 
details on the :post header.

The user-error halts export.

HTH,
Chuck