investigate switching to `uncaughtExceptionMonitor` event

Node v12.17.0 added the [`uncaughtExceptionMonitor` process event](https://nodejs.org/docs/latest-v12.x/api/all.html#process_event_uncaughtexceptionmonitor), separate from `uncaughtException`, I'm *guessing* to provide a mechanism for doing something with these without otherwise changing node's default `uncaughtException` handler. It would be good to use this when possible. Perhaps we guard on the current node version, or we wait until v12.17 is a base supported version.