PL/SQL :: Error In Modifying Object Value In Triggers Defined On Object Tables

While practicing with Triggers, the following error was encountered. An Object Type and an object Table are created.

create or replace
type typPerson is object
(id number,
firstname varchar2(30),
lastname varchar2(30)
[code].........

I executed the below insert statement, and I got the following error.

SQL> insert into person_obj_tab values (10,'Object1','From Trigger');
insert into person_obj_tab values (10,'Object1','From Trigger')
*
ERROR at line 1:
ORA-03113: end-of-file on communication channel
Process ID: 4153
Session ID: 136 Serial number: 305
[code]......

SQL> insert into person_obj_tab values (10,'Object','Original');

1 row created.Question:

1) Trigger of version 1 did not report any error during compilation, but during DML execution, hangs for sometime and gives the above error.
2) Whether direct assignment of Objects of greater size is possible inside triggers built on object Tables?
3) Suppose an object contain multiple attributes (say more than 20), then how to assign them inside a trigger?