Bug with different parameters

typical_workaround.sql

with t(a,b) as (select * from table(ku$_objnumpairlist(ku$_objnumpair(1,null))))
select
       json_object(
         KEY 'a' VALUE a,
         KEY 'b' VALUE b absent on null
       ) c2,
       json_object(
         KEY 'a' VALUE a+0,
         KEY 'b' VALUE b null on null
       ) c1,
       json_object(
         KEY 'a' VALUE a+0+0,
         KEY 'b' VALUE b absent on null
       ) c3
 from  t;

C2                                       C1                                       C3
---------------------------------------- ---------------------------------------- ----------------------------------------
{"a":1}                                  {"a":1,"b":null}                         {"a":1}