"couldn't join sampler thread" on MacOS 14.7 for rust program until samply signed

I'm putting this here in case it is useful to anyone else.

Although the documentation said that running `samply setup` to sign the binary on MacOS is only needed for attaching to an already running process, I found that until I ran `samply setup` I was getting a crash with the error message "couldn't join sampler thread" after my (Rust) program had finished running under samply.