How to find Server Log errors

CREATE TABLE LOG_ERRORS
( "ERR_NUM" NUMBER,
"ERR_MSG" VARCHAR2(3000 BYTE),
"ERR_DATETIME" TIMESTAMP (6),
"ERR_DEPTH" VARCHAR2(2000 BYTE)
);

Create trigger For If any query or server error happen in the database errnum,errmsg,querystatment insert into the bove table

create or replace trigger log_err after servererror
on schema
declare
v_num number;
sql_text ora_name_list_t;
v_msg varchar2(3000);
v_depth varchar2(2000);
stmt_ varchar2(2000) := null;

begin
v_num := server_error(1);
v_msg := server_error_msg(1);
--v_depth := server_error_param;
for i in 1 .. ora_sql_txt(sql_text) loop
stmt_ := stmt_ || sql_text(i);
end loop;

insert into log_errors(err_num, err_msg, err_datetime, err_depth) values(abs(v_num),v_msg, sysdate,stmt_);
end;