I just discovered this by accident and it should help someone else. For those that have text files for .rules and running OH 3. The error message given often is a DSL Rule Number X errored out.
For those that have a lot of rules, this is very hard to determine what the rule name is causing the issue. Often, the errored log line has NO line number to reference.
I was in the OH 3 Admin GUI and clicked on Rules and there I saw all the DSL Rule numbers tied to actual rules names. Now its very easily to determine which rule has an issue based on the DSL Rule number.