Potential for incorrect results or NPE when full outer USING join has null key value

create or replace temp view v1 as values (1, 2), (null, 7) as (c1, c2);
create or replace temp view v2 as values (2, 3) as (c1, c2);

select explode(array(c1)) as x
from v1
full outer join v2
using (c1);

-1   <== should be null
1
2

create or replace temp view v1 as values ('1', 2), (null, 7) as (c1, c2);
create or replace temp view v2 as values ('2', 3) as (c1, c2);

select explode(array(c1)) as x
from v1
full outer join v2
using (c1);

23/06/25 17:06:39 ERROR Executor: Exception in task 0.0 in stage 14.0 (TID 11)
java.lang.NullPointerException
	at org.apache.spark.sql.catalyst.expressions.codegen.UnsafeWriter.write(UnsafeWriter.java:110)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage3.generate_doConsume_0$(Unknown Source)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage3.smj_consumeFullOuterJoinRow_0$(Unknown Source)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage3.wholestagecodegen_findNextJoinRows_0$(Unknown Source)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage3.processNext(Unknown Source)
	at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
	at org.apache.spark.sql.execution.WholeStageCodegenEvaluatorFactory$WholeStageCodegenPartitionEvaluator$$anon$1.hasNext(WholeStageCodegenEvaluatorFactory.scala:43)
...