The ORA_IS_SERVERERROR returns a true or false value as a BOOLEAN datatype when the error is on the error stack.
SQL> SQL> SQL> BEGIN 2 IF ora_is_servererror(4082) THEN 3 dbms_output.put_line('ORA-04082 error thrown.'); 4 END IF; 5 END; 6 / PL/SQL procedure successfully completed. SQL>