fix: if a table does not exist, use an empty schema

[mikix]

(Instead of erroring out.)

This helps in cases where some tables get optionally created (like the ETL completion tables), because Athena generates an exception for that.

Checklist

• [x] Consider if documentation (like in docs/) needs to be updated
• [x] Consider if tests should be added
• [x] Update template repo if there are changes to study configuration