I am trying to compile the below code at time of compiling i am getting errors stating as 😕👇

CREATE 
OR REPLACE TRIGGER A_TRI BEFORE 
DELETE
    OR INSERT 
    OR 
    UPDATE
        ON tri FOR EACH ROW 
        DECLARE v_user VARCHAR2(50);
v_Date VARCHAR2(50);
BEGIN
    SELECT
        USER,
        to_char(sysdate, 'DD/MON/YYYY H24:MM:SS') INTO v_user,
        v_date 
    FROM
        DUAL;
IF INSERTING 
THEN
    INSERT INTO
        tri_auditing (ID, LAST_UPDATE_DATE, LAST_UPDATE_BY_OLD, LAST_UPDATED_BY_NEW, ACTION) 
    VALUES
        (
            tri_auditing_seq.NEXTVAL, v_date, NULL, :NEW.v_user, 'inserting'
        )
;
DBMS_OUTPUT.PUT_LINE(v_user || ' is inserting');
ELSIF UPDATING 
THEN
    INSERT INTO
        tri_auditing (ID, LAST_UPDATE_DATE, LAST_UPDATE_BY_OLD, LAST_UPDATED_BY_NEW, ACTION) 
    VALUES
        (
            tri_auditing_seq.NEXTVAL, v_date, :OLD.v_user, :NEW.v_user, 'updating'
        )
;
DBMS_OUTPUT.PUT_LINE(v_user || ' is updating');
ELSIF DELETING 
THEN
    INSERT INTO
        tri_auditing (ID, LAST_UPDATE_DATE, LAST_UPDATE_BY_OLD, LAST_UPDATED_BY_NEW, ACTION) 
    VALUES
        (
            tri_auditing_seq.NEXTVAL, v_date, :OLD.v_user, :NEW.v_user, 'deleting'
        );
DBMS_OUTPUT.PUT_LINE(v_user || ' is deleting');
ELSE
    DBMS_OUTPUT.PUT_LINE('Invalid event');
END IF;
END;

I have tried to alter auditing table as well but not getting any results.
errors i given below

• Error(12,57): PLS-00049: bad bind variable ‘NEW.V_USER’

• Error(17,51): PLS-00049: bad bind variable ‘OLD.V_USER’

• Error(17,64): PLS-00049: bad bind variable ‘NEW.V_USER’

• Error(22,51): PLS-00049: bad bind variable ‘OLD.V_USER’

• Error(22,64): PLS-00049: bad bind variable ‘NEW.V_USER’