BUG #14354: Wrong interpretation of JSON 'null'

The following bug has been logged on the website:

Bug reference: 14354
Logged by: Kouber Saparev
Email address: kouber(at)gmail(dot)com
PostgreSQL version: 9.4.5
Operating system: Fedora
Description:

Trying to pass 'null' to jsonb_each_text() results in an ERROR, while at the
same time it is considered a valid JSON value. This behaviour seems quite
inconsistent - either such a value should be considered invalid in general,
either the function should treat it as a normal NULL instead.

db=# select 'null'::jsonb;
jsonb
-------
null
(1 row)

db=# select jsonb_each_text('null'::jsonb);
ERROR: cannot call jsonb_each_text on a non-object

db=# select jsonb_each_text(NULL);
jsonb_each_text
-----------------
(0 rows)