ErrorHandler is a public interface for which a user can even provide a custom implementation, however, the Javadocs are non existent. What are the pre- and post-conditions and is it for example ok to throw an exception?
In case of the later, what will the app do?
Also the online docs seem to imply that the ErrorHandler gets used for all sort of indexing (batch, event and programmatic indexing). See section "3.8. Exception Handling Configuration". We need to make the differences clear to the user.