I have fixed this issue after some experimenting. I'd tried various 'apt-get purge' and uninstall approaches, but whenever I tried the reinstall I got the above error message.
Eventually I tried a purge and then removed *all* mentions of emacs in /etc/ and /var/.
After this, I tried (one more time) and I now have a working Emacs, with AUCTeX installed properly, which is what I was after.
I have fixed this issue after some experimenting. I'd tried various 'apt-get purge' and uninstall approaches, but whenever I tried the reinstall I got the above error message.
Eventually I tried a purge and then removed *all* mentions of emacs in /etc/ and /var/.
After this, I tried (one more time) and I now have a working Emacs, with AUCTeX installed properly, which is what I was after.