Ok, I think I misunderstood error. I thought that an email would be sent by error.create, but on re-reading the docs I think I have to throw the resulting error object to get an email. So different question: How can I send an email to the script owner? I'd prefer not to have to maintain my own record of the script owner

You might wanna go to Setup > Company > Email Preferences > Email Options Select the first Radio button and input your email address. It will send an email if you do error.create and the notify the owner if the checkbox is checked.