BUG #16636: Upper case issue in JSONB type

The following bug has been logged on the website:

Bug reference: 16636
Logged by: ChandraKumar Ovanan
Email address: osaimar19(at)gmail(dot)com
PostgreSQL version: 11.0
Operating system: Windows 10
Description:

Hi All,
Below example which I was execute query in postgres.
The problem statement here, when I use upper case function by converting
JSONB object has Null value,
Then I getting below error.
Please could fix it defect or why this behavior on postures,required
clarification

Error message:
SQL Error [22P02]: ERROR: invalid input syntax for type json
Detail: Token "NULL" is invalid.
Where: JSON data, line 1: ...E": "2018-01-10", "NAME": "TEST3"}, {"DATE":
NULL...

CREATE TABLE logs(id serial, data JSONB);
INSERT INTO logs VALUES
(1,
'[{"name":"test1","date":"2020-11-11"},{"name":"test2","date":"2018-01-10"}]'),
(2,
'[{"name":"test3","date":"2020-05-18"},{"name":"test4","date":"null"}]');

SELECT * FROM logs WHERE data @> '[{"date":null}]';
SELECT * FROM logs WHERE data @> '[{"date":"2018-01-10"}]';
SELECT * FROM logs WHERE data @> '[{"date":"2018-01-11"}]';
SELECT * FROM logs WHERE data @> '[{"name":"test4"}]';
SELECT * FROM logs WHERE lower(data::text)::jsonb @>
lower('[{"date":"2018-01-10"}]')::jsonb ; --working
SELECT * FROM logs WHERE upper(data::text)::jsonb @>
upper('[{"date":"2018-01-10"}]')::jsonb ; --Not working