DO
$$
DECLARE
r record;
BEGIN

r := null;

if r is null    -- ERROR:  record "r" is not assigned yet
then
end if;

END
$$;

select null into r;

r:=row(null);

DO $$
DECLARE
r record;
BEGIN

r := null;

  BEGIN
    IF r IS NOT NULL THEN
        raise notice 'R IS INITIALIZED';
    END IF;
  EXCEPTION
    WHEN OTHERS THEN
        raise notice 'R IS NOT INITIALIZED';
  END;

END
$$;