The error can occur, if you try to start the spell and grammar check dialog before LO has called the interface to check the first sentence. I added a bug fix for this in my last update today
The same error occurs on ubuntu 18.04lts along with Libreoffice Writer -7.x -, when I use the F7 function key. It works not too well using the Spell Check option.
Version: 7.1.0.0.alpha0+
Build ID: a8c218a52a639b0e7f689dea878a0421702628e0
CPU threads: 4; OS: Linux 4.15; UI render: default; VCL: gtk3
Locale: it-IT (it_IT.UTF-8); UI: it-IT
TinderBox: Linux-rpm_deb-x86_64@86-TDF, Branch:master, Time: 2020-09-25_22:25:07
Calc: threaded
I don’t know if the problem is rare or not. It occurs if someone is very fast and starts the dialog before any iteration in the background was done.
A new release at this point is not a good idea I think. There was some other changes and I’m working on some bug fixes right now. Could we shift it a few days?
Yes, this is a good idea. But the change is hidden in a huge commit. Is it possible to get back to the code of 5.1. Only three lines are the solution to solves the bug: