https://discuss.google.dev/t/webhook-start-block-requires-trailing-comma-which-breaks-syntax/343698
Webhook START: block requires trailing comma - which breaks syntax - AppSheet Q&A - Google...
trailing commawebhookstart
https://pawelgrzybek.com/trailing-comma-in-ecmascript2017-function-parameter-list/
Trailing comma in ECMAScript 2017 function parameter list | pawelgrzybek.com
Object and array literals already allow us to leave a trailing comma. ECMAScript 2017 adds the same functionality to the function parameter list.
trailing commaecmascriptlist