无法识别codeigniter事务中的db错误

Question

所以我有我的数据库事务的代码：

$to_return = true;
        $this->db->trans_begin();

        $this->insert_arrest_details($data);
        $this->update_barangay($data['barangay_id']);
        $this->insert_arresting_officers($data);
        $folders = $this->insert_violators($data);  
        $this->insert_arrest_booking_form($data);   
        $this->insert_case_report($data);
        $this->insert_seizing_officers($data['case_id'],json_decode($data['seizing_officers']));
        $this->insert_items(json_decode($data['items']));
        $this->insert_nitems(json_decode($data['nitems'])); 
        $this->insert_violator_items(json_decode($data['items']));  
        $this->insert_violator_nitems(json_decode($data['nitems']));


        if($this->db->trans_status() === FALSE){
            $array['error_message'] = $this->db->_error_message();
            $array['error_number'] = $this->db->_error_number();

            $this->db->trans_rollback();

            $to_return = $array;
        }else{  
            $img_success = $this->move_violators_images($folders);
            $img_success = $this->move_items_images($data['case_id']);  
            $img_success = 1;
            if($img_success == 1){
                $this->db->trans_commit();
            }else{
                $this->db->trans_rollback();
                $to_return = false;
            }

        }       
        return $to_return;

我的问题是，如果错误（例如）发生在$ this-＆gt; insert_arrest_details（）;我的代码没有收到错误。它返回如下内容：

  

＆＃34; ERROR_MESSAGE＆＃34;：＆＃34;＆＃34;＆＃34; ERROR_NUMBER＆＃34;：0

但是当我尝试仅运行1个方法并且该方法失败时，我的代码就能够得到错误。为什么会这样？

非常感谢您的回复。