That was it, invalid characters in a test method string. Thanks, @Pravin Barton and @Alex Woodhead!

@Brett Saviano @Evgeny Shvarov You listed VSCode plusses, thanks. How about what Studio does that VSCode plus free plugins still do not? One of our programmers complained about debugging as of July 2022. Is it on par now?
 

I'll watch it, thanks, Raj. I have to say though that I really prefer searchable text that can be visually scanned diagonally in 5 minutes as opposed to watching a 45-minute video. Oh well...