PPL stats aggregation fails with NPE when index has zero documents

[qianheng-aws]

Bug

When running any PPL stats aggregation on an index with no documents, the query fails with a NullPointerException instead of returning an empty or zero result.

Reproduce

PUT /test_empty_index
source=test_empty_index | stats sum(amount), count()

Error response 500:

Caused by: java.lang.NullPointerException
  at org.opensearch.sql.expression.aggregation.CountAggregator.iterate(...)

Expected

Should return sum(amount) = null, count() = 0 gracefully.

Version

OpenSearch 2.17 with SQL plugin 2.17.0

[github-actions]

Possible Duplicate

Found 2 possible duplicate issue(s):

• PPL stats command throws NullPointerException on empty index #4 — PPL stats command throws NullPointerException on empty index
• NullPointerException when running stats aggregation on index with no documents #7 — NullPointerException when running stats aggregation on index with no documents

If this is not a duplicate, please comment on this issue and the autoclose label will be removed automatically.

Otherwise, this issue will be automatically closed in 3 days.

🤖 Generated with Claude Code

[qianheng-aws]

test

[qianheng-aws]

Possible Duplicate

Found 2 possible duplicate issue(s):

• PPL stats command throws NullPointerException on empty index #4 — PPL stats command throws NullPointerException on empty index
• NullPointerException when running stats aggregation on index with no documents #7 — NullPointerException when running stats aggregation on index with no documents

If this is not a duplicate, please comment on this issue and the autoclose label will be removed automatically.

Otherwise, this issue will be automatically closed in 3 days.

🤖 Generated with Claude Code

No duplication.

[qianheng-aws]

test