Yesterday, Apple released the first beta of macOS 10.15 Catalina to users in the Apple Beta Software Program. If you're in the program and have installed the beta, well, surprise! Scripts and apps written for iTunes will not work on it. That's because there is no version of iTunes in the beta for scripts and apps to work with.
As you are no doubt aware, Apple has replaced iTunes with the Music, Apple TV, Podcasts and Books apps. Between now and the official release of Catalina in the fall, I will be updating very many scripts to work with the Music and Apple TV apps—Podcasts and Books do not have AppleScript support.
Providentially, scripting the Music and Apple TV apps is very much like scripting for iTunes. Their scripting definitions are virtually identical. In many cases, for very simple scripts, updating will merely require changing the target from "iTunes" or "com.apple.iTunes" to "Music"/"com.apple.Music" or "Apple TV"/"com.apple.TV". More elaborate scripts may require additional modifications and security accommodations.
Thus, there will essentially be two sets of scripts on this site: those written for iTunes that can only run under macOS 10.14 and earlier and those for the newer media apps that can only run under macOS 10.15 and later.
I hope to have a first batch of Catalina-compatible scripts posted in about a week.