kill-region: Text is read-only: #<buffer *gnuplot*>

[sjLambda]

I get this error in the middle of producing a dozen or so plots from an org file.

kill-region: Text is read-only: #<buffer gnuplot>

This is an old file that used to be able to generate the plots without errors. I can recreate the plots individually through the org-file fine. Only when I run them all at once, I get this error. I instrumented the kill-region function for Edebug to produce this trace:

kill-region(1 29)
kill-line()
gnuplot-trim-gnuplot-buffer()
run-hooks(gnuplot-after-plot-hook)
gnuplot-send-string-to-gnuplot(" " buffer)
gnuplot-send-region-to-gnuplot(1 575 buffer)
gnuplot-send-buffer-to-gnuplot()
org-babel-execute:gnuplot(" ...")

These are the versions:

: Emacs version: GNU Emacs 27.0.50 (build 1, x86_64-apple-darwin15.6.0, NS appkit-1404.47 Version 10.11.6 (Build 15G20015))
: org version: 9.1.13
: gnuplot 5.2 patchlevel 2
: gnuplot.el Version: 0.7.0

[conao3]

Please attach the issue org-mode file and please use Emacs 26 instead of 27.