I have a pipeline function. If I catch an exception, I want to return no lines. Even if the exception occurs after the first utilisation of pipe row.

CREATE TYPE a_r IS OBJECT (a1 VARCHAR (1), a2 VARCHAR (1));

CREATE TYPE a_t IS TABLE OF a_r;

CREATE or replace FUNCTION get_a
    RETURN a_t
    PIPELINED
IS
BEGIN
    FOR c IN (SELECT '1' a , '2' b FROM DUAL)
    LOOP
        PIPE ROW (a_r(c.a,c.b));
    END LOOP;
    FOR a
            IN (SELECT 'a2' a,
                       'b' b
                  FROM DUAL)
        LOOP
            PIPE ROW (a_r(a.a,a.b));
        END LOOP;
exception
        WHEN VALUE_ERROR
        THEN
            DBMS_OUTPUT.put_line ('VALUE_ERROR');
        WHEN OTHERS
        THEN
            DBMS_OUTPUT.put_line ('other');
    
END;

select * from table(get_a())

1,2 are returned. But I want nothing to be returned. Is there a way to write cancel what was piped in the exception block?

code