Catch bad queries in Oracle.

caught_errors.sql

create table caught_errors (
  dt        date,               
  username  varchar2( 30), -- value from ora_login_user
  msg       varchar2(2000),
  stmt      varchar2(2000)
);


create or replace trigger catch_errors
   after servererror on database
declare
   sql_text ora_name_list_t;
   msg_     varchar2(2000) := null;
   stmt_    varchar2(2000) := null;
begin

  for depth in 1 .. ora_server_error_depth loop
    msg_ := msg_ || ora_server_error_msg(depth);
  end loop;

  for i in 1 .. ora_sql_txt(sql_text) loop
     stmt_ := stmt_ || sql_text(i);
  end loop;

  insert into 
    caught_errors (dt     , username      ,msg ,stmt )
           values (sysdate, ora_login_user,msg_,stmt_);
end;
/

Add this trigger, then just select * from caught_errors;
Simple!

WARNING - dropping this table without removing the trigger will cause an error, which will try to write to the table, which will cause an error and so on. You have been warned.