Bug: Re: ob-scheme.el has two problems: not killing a misbehaving interpreter and sometimes returns nil [9.1.9 (release_9.1.9-65-g5e4542 @ /usr/share/emacs/26.2/lisp/org/)]

[Vladimir Nikishkin <lockywolf@gmail.com>]

Remember to cover the basics, that is, what you expected to happen and
what in fact did happen.  You don't know how to make a good report?  See

     https://orgmode.org/manual/Feedback.html#Feedback

Your bug report will be posted to the Org mailing list.
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The super-pedestrian patch I wrote to patch this issue is:

diff --git a/usr/src/emacs/lisp/org/ob-scheme.el b/usr/share/emacs/26.2/lisp/org/ob-scheme.el
index 798cf4e..1df4df9 100644
--- a/usr/src/emacs/lisp/org/ob-scheme.el
+++ b/usr/share/emacs/26.2/lisp/org/ob-scheme.el
@@ -175,7 +175,10 @@ is true; otherwise returns the last value."
 		(geiser-debug-show-debug-p nil))
 	    (let ((ret (geiser-eval-region (point-min) (point-max))))
 	      (setq result (if output
-			       (geiser-eval--retort-output ret)
+			       (let ((g-r-o (geiser-eval--retort-output ret)))
+				 (if g-r-o
+				     g-r-o
+				   "Geiser-eval--retort-output returned nil.\nThe interpreter produced no output\nor there is a bug in geiser (likely!)"))
 			     (geiser-eval--retort-result-str ret "")))))
 	  (when (not repl)
 	    (save-current-buffer (set-buffer repl-buffer)


Emacs  : GNU Emacs 26.2 (build 1, x86_64-slackware-linux-gnu, GTK+ Version 3.24.10)
 of 2019-07-18
Package: Org mode version 9.1.9 (release_9.1.9-65-g5e4542 @ /usr/share/emacs/26.2/lisp/org/)
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Vladimir Nikishkin (MiEr, lockywolf)