Upgrading to Emacs 29-1
It appears upgrading my Anaconda Python distribution killed my Emacs, so I figured I'd try upgrading to the latest version to see if that fixed things. It did :)
Since upgrading Emacs to 29.1 no longer required the manual configuration changes I had to make when upgrading to 28.2, I'll document the procedure I used on MacOS Ventura 13.6.1