Description
```
val sqlDf = spark.sql("select k,v from (select str_to_map('') as map_col from range(2)) tbl lateral view explode(map_col) as k,v")
sqlDf.show
```
The sql throws NPE exception.
```
val sqlDf = spark.sql("select k,v from (select str_to_map('') as map_col from range(2)) tbl lateral view explode(map_col) as k,v")
sqlDf.show
```
The sql throws NPE exception.