Post aggregators in SQL based ingestion with rollups

[cryptoe]

While running query :

REPLACE INTO country_shard_test_1 OVERWRITE ALL
SELECT Country,Capital,    THETA_SKETCH_INTERSECT(
      DS_THETA(Country),
      DS_THETA(Capital)
    ) as sketch FROM TABLE(
  EXTERN(
    '{"type":"http","uris":["https://static.imply.io/lookup/country.tsv"]}',
    '{"type":"tsv","findColumnsFromHeader":true}',
    '[{"name":"Country","type":"string"},{"name":"Capital","type":"string"},{"name":"ISO3","type":"string"},{"name":"ISO2","type":"string"}]'))
  group by 1,2
  PARTITIONED BY ALL

We get an unknown error :

UnknownError: java.util.NoSuchElementException (Stack trace)
Failed task ID: query-0bc9b9c3-de75-416c-bfdb-6ab802871826 (on host: localhost:8100)
Debug: get query detail archive
Full stack trace
java.util.NoSuchElementException
    at java.base/java.util.Collections$EmptyIterator.next(Collections.java:4210)
    at com.google.common.collect.Iterators.getOnlyElement(Iterators.java:297)
    at com.google.common.collect.Iterables.getOnlyElement(Iterables.java:285)
    at org.apache.druid.msq.exec.ControllerImpl.makeDimensionsAndAggregatorsForIngestion(ControllerImpl.java:1646)
    at org.apache.druid.msq.exec.ControllerImpl.generateDataSchema(ControllerImpl.java:1431)
    at org.apache.druid.msq.exec.ControllerImpl.makeQueryDefinition(ControllerImpl.java:1398)
    at org.apache.druid.msq.exec.ControllerImpl.initializeQueryDefAndState(ControllerImpl.java:523)
    at org.apache.druid.msq.exec.ControllerImpl.runTask(ControllerImpl.java:346)
    at org.apache.druid.msq.exec.ControllerImpl.run(ControllerImpl.java:296)
    at org.apache.druid.msq.indexing.MSQControllerTask.run(MSQControllerTask.java:192)
    at org.apache.druid.indexing.overlord.SingleTaskBackgroundRunner$SingleTaskBackgroundRunnerCallable.call(SingleTaskBackgroundRunner.java:477)
    at org.apache.druid.indexing.overlord.SingleTaskBackgroundRunner$SingleTaskBackgroundRunnerCallable.call(SingleTaskBackgroundRunner.java:449)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:829)

How should we handle post aggregators in SQL-based ingestion while doing rollup q's.