If I try to call json_object with a NULL key, it fails:

sqlite> SELECT id,json_object(key,value) FROM (SELECT 1 AS id, NULL AS key, 2 AS value);
Runtime error: json_object() labels must be TEXT

However, doing so with json_group_object doesn't give an error, but instead just omits the key entirely (which produces invalid JSON):

sqlite> SELECT id,json_group_object(key,value) FROM (SELECT 1 AS id, NULL AS key, 2 AS value) GROUP BY id;
1|{:2}

jsonb_group_object has this problem as well.

Also, is there a way to get an empty object if the key is NULL? In my case, the key and value are from a left join, so if the key is NULL then it's the only one and the value will also be NULL, so I want to ignore that column.