Clicking OK got me a second error:
This error was somewhat puzzling as there is no code on Switch Company:
I spent a bit of time investigating, and a lot of time cursing, before I established the cause of the problem and fixed it.
I’ve not had time to get properly sorted out with source control of the Dexterity; I am controlling the source, but don’t have it integrated with Dex Utils.
This is the direct cause of my problem; I am currently exporting and importing using text files to get the code into the new dictionaries. It turns out that during the export/import I lost a couple of the script files. Redoing the export and import brought all of the files across and the error went away.
From not having had time to integrate source control with Dexterity, I caused a fairly substantial loss of time, so this is something I need to progress quickly. With the recent addition of a more technical resource into my team, I can delegate this task.