"JSON does not support infinite date values"

Hi,

As far as I'm aware, JSON has no data types as such, and so why is
Postgres (9.4.1) attempting to impose its own nonsense constraints ?
Surely it should just insert the word 'infinity' into the JSON output,
just like it displays in a simple SQL query ?

create table app_test.foo(a text,b date,c date,d boolean);

create view app_test.bar as select * from app_test.foo where
b<=now()::date and c>=now()::date and d=true;

insert into app_test.foo(a,b,c,d) values ('zzz','2014-12-31','2014-02-01',true);
insert into app_test.foo(a,b,c,d) values ('zzz','2015-02-01','infinity',true);

foobar=> select * from app_test.bar where a='zzz' order by c asc limit 1;
a | b | c | d
-----+------------+----------+---
zzz | 2015-02-01 | infinity | t
(1 row)

CREATE FUNCTION app_test.foobar(p_a text) RETURNS json AS $$
DECLARE
v_row app_test.bar%ROWTYPE;
v_json json;
BEGIN
select * into strict v_row from app_test.bar where a=p_a order by c asc limit 1;
select row_to_json(v_row) into v_json;
return v_json;
END;
$$ LANGUAGE plpgsql;

foobar=> select app_test.foobar('zzz');
ERROR: date out of range
DETAIL: JSON does not support infinite date values.
CONTEXT: SQL statement "select row_to_json(v_row)"
PL/pgSQL function app_test.foobar(text) line 7 at SQL statement