You can close it. We should do a new release of Communications right before Octave 7 comes out.

Thanks, I committed it at http://hg.code.sf.net/p/octave/communications/rev/ace112d772c3

Quoting jwe from bug #61551:

> The global 'error_state' variable has been useless for quite some time now.  It's been removed on the default branch (what will become version 8.1 in about a year).  Since about 6 years ago, it has never had a value other than 0 in Octave code and is no longer useful for checking whether an error has occurred because exceptions are thrown, so checking the state of a variable after an error occurs is not useful except inside a 'catch' clause that handles 'octave::execution_exception'.
> All uses of this variable should be removed from the video package and any other packages that still use it.  You should have been seeing a warning at compile time about it being deprecated since before version 6 was released (it was marked as deprecated in May 2019).

This also applies to the communications package.
I'll attach a possible patch as soon as I'll have a bug number.