Remove assertion

Author: kanoshiou

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/planner/LocalExecutionPlanner.java

@@ -359,7 +359,6 @@ private PhysicalOperation planExchangeSource(ExchangeSourceExec exchangeSource,
 
     private PhysicalOperation planTopN(TopNExec topNExec, LocalExecutionPlannerContext context) {
         final Integer rowSize = topNExec.estimatedRowSize();
-        assert rowSize != null && rowSize > 0 : "estimated row size [" + rowSize + "] wasn't set";
         PhysicalOperation source = plan(topNExec.child(), context);
 
         ElementType[] elementTypes = new ElementType[source.layout.numberOfChannels()];