Oracle Trigger - How can I capture and correct on the fly ORA-01847

Question

Oracle Trigger - How can I capture and correct on the fly ORA-01847 day of month must be between 1.
I have a table that has a date column. Sometimes an invalid date is passed and I'd like to capture and initilize the incoming value to null and have it inserted without error. Currently I get ORA-01847 day of month must be between 1.
Example:
create table ep1
col_1 number,
col_2 date
Now if a user does the following, I want no error to occure but rather for the date value to be set to null and inserted.
insert into ep1 values('1', '41-JAN-13')
The insert may come from any client and I can't change the calling code hence can't used a precedure to replace the insert. I'm guessing there is some way to catch system level exceptions on the DB level. This doesn't need to be nice, it just needs to work.
Here is the question on experts exchange. I'm told there is no way, but there must be. After all the exception is on a DB system level and I would think one could extend or override these, or disable them.
http://www.experts-exchange.com/Database/Oracle/PL_SQL/Q_23045306.html

Answer 1

SQL> declare
  2     wrong_month      exception;
  3     pragma exception_init (wrong_month, -1843);
  4  begin
  5    begin
  6      insert into emp (empno, hiredate)
  7      values (2345,to_date('13/25/81','MM/DD/YY'));
  8    exception
  9      when wrong_month then
10      dbms_output.put_line('I caught the bad month');
11      insert into emp (empno, hiredate)
12      values (2345,null);
13    end;
14  end;
15  /
I caught the bad month
PL/SQL procedure successfully completed.
SQL>
SQL> select * from emp
  2  where empno = 2345;
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
      2345Note the 1843 error vice 1847. It can be done outside of a trigger.