I am continually twarted by the latest CEP changes in Photoshop.
Today I found that when I call ExtendScript's app.open() method in Photoshop v23.x, it throws an exception with the message: "Error: Expected a reference to an existing File/Folder".
The file in question does, in fact, exist. Furthermore, I find that this exception is thrown for any file I attempt to open using ExtendScript, regardless of the directory in which it resides. And yes, I tried files on my desktop and in the Download folders as well.
The same code works as expected on Windows. This fact leads me to believe that perhaps macOS Monterey sandbox rules are coming into play here, but I am attempting to access the very files that my extension placed on the disk in the first place. For that reason, I expected sandbox rules to permit reading them back.