The spec for the loop operation says that, for both storeErrorsAsEntity and storeFailuresAsEntity, if the other one is not specified, to put both failures and errors into the same entity on the entity map. However, the astrolabe documentation says that storeFailuresAsEntity should never be specified, and instead should only use storeErrorsAsEntity. This results in all of the tests in atlas-drivers-testing storing both failures and errors under the same key in the entity map (either "errors" or "failures" depending on which was specified). Given that in all tests both failures and errors are put into the same array, it does not make sense to implement the logic ensuring that failures are stored into a different array as that case never occurs.