Non-deterministic NPE with sum/case/when query

[dang-stripe]

We're getting non-deterministic NPEs on a null-enabled query that looks like this. We're using Pinot 1.2.

set enableNullHandling = true;
select m_id,
  sum(
    case
      when outcome = 'success' then 1
      else 0
    end
  ) as success,
  sum(
    case
      when outcome = 'failed' then 1
      else 0
    end
  ) as failed,
  sum(
    case
      when outcome = 'invalid' then 1
      else 0
    end
  ) as invalid,
from example_table 
where
  some_filter_condition = 'value'
group by 1
order by (success + failed + invalid) desc

Unfortunately, there's no stacktrace in the failure.

[2025-01-21 22:50:01.843739] ERROR [BaseCombineOperator] [pqw-92:90] Caught exception while processing query: QueryContext{_tableName='example_table_REALTIME', _subquery=null, _selectExpressions=[m_id, sum(case(equals(outcome,'success'),'1','0')), sum(case(equals(outcome,'failed'),'1','0')), sum(case(equals(outcome,'invalid'),'1','0'))], _distinct=false, _aliasList=[null, success, failed, invalid], _filter=(some_filter_condition = 'value'), _groupByExpressions=[m_id], _havingFilter=null, _orderByExpressions=null, _limit=10, _offset=0, _queryOptions={enableNullHandling=true}, _expressionOverrideHints={}, _explain=false} [2025-01-21 22:50:01.843748] java.lang.NullPointerException: null

Switching it to use COUNT(*) FILTER instead of sum/case/when works reliably.

COUNT(*) FILTER (WHERE outcome = 'success') as success,
COUNT(*) FILTER (WHERE outcome = 'failed') as failed,
COUNT(*) FILTER (WHERE outcome = 'invalid') as invalid,

I've also confirmed there's no null values for the outcome field.

cc @Jackie-Jiang