Spark 2.0 GROUP BY NULLS

Question

Working on migrating some queries from Spark 1.5 to Spark 2.0

The query is the following:

SELECT 
    users.age AS users_age,

  NULL

 AS users_running_total_on_null
FROM users

GROUP BY users.age
ORDER BY users_age 
LIMIT 1

First of all, I know in Spark, null checks don't work when used in a group by, and calling LENGTH() on the value and null checking works correctly.

Running the above query, I get the following error:

SQL Error: java.lang.IllegalArgumentException: Unrecognized type name: null\"

Any ideas what the problem is?