How to catch Oracle db error in Codeignitor 3

I am using $db->error() to catch SQL errors but when I use it with oracle it throws an error along with the HTML page and is unable to rollback. I already changed $db['default']['db_debug'] = false; but still getting HTML page.

    $db = $this->load->database($db_name, TRUE);
    $db->trans_begin();
    $ret = array();
    foreach ($query['query'] as $value) {
        $db->query($value);
        $error = $db->error();
        if($error['message'] != null){
            echo '<pre>';print_r($error);echo '</pre>';
            array_push($ret,$error['message']);
        }
     }
    if ($db->trans_status() === FALSE) {
        $db->trans_rollback();
        return $data['msg'] = $ret;
    }else{
        $db->trans_commit();
        return $data['msg'] = true;
    }

Code is working perfectly fine when getting SQL DB error and getting this error with oracle

    <div style="border:1px solid #dd4814;padding-left:20px;margin:10px 0;">

    <h4>A PHP Error was encountered</h4>

    <p>Severity: Warning</p>
    <p>Message:  oci_execute(): ORA-00001: unique constraint (C##TEST.PK_GROUPS) violated</p>
    <p>Filename: oci8/oci8_driver.php</p>
    <p>Line Number: 281</p>
    <p>Backtrace:</p>
                <p style="margin-left:10px">
                File: C:\xampp\htdocs\gen-script-api\application\models\common_model.php<br />
                Line: 297<br />
                Function: query             </p>
    
                <p style="margin-left:10px">
                File: C:\xampp\htdocs\gen-script-api\application\controllers\Common_Ctrl.php<br />
                Line: 79<br />
                Function: insert_to_ticket              </p>

                <p style="margin-left:10px">
                File: C:\xampp\htdocs\gen-script-api\index.php<br />
                Line: 308<br />
                Function: require_once              </p>
</div>
<pre>Array
(
    [code] => 1
    [message] => ORA-00001: unique constraint (C##TEST.PK_GROUPS) violated
    [offset] => 0
)

    </pre>["ORA-00001: unique constraint (C##TEST.PK_GROUPS) violated"]

I can see an error coming by $db->error() but how can I stop the HTML page from coming along with so i can receive this error from frontend?