When the Spark import incremental dump code runs, but no new dump exists, we get this observability email:

Hi! 👋

A new data dump has been imported into the spark
cluster.

Dump name:
Import time: 2021-05-12 13:00:06.277912

Your Friendly Neighbourhood Brainzbot 🤖

The dump name is blank, so something happened. The importer should catch this and send an email to listenbrainz-exceptions@ with details, instead of sending a useless blank observability email.