datatable server side processing gives error - ajax

Question

I am new in codeigniter-4 and i am inplementing datatable server side processing.
I found following error:
"DataTables warning: table id=admin_user_datatable - Requested unknown
parameter '0' for row 0, column 0. For more information about this
error, please see http://datatables.net/tn/4"
After this error, data is loading in server table.
controller:
public function ajaxDataTables()
{
$params['draw'] = #$_POST['draw'];
$start = #$_POST['start'];
$length = #$_POST['length'];
$search_value = #$_POST['search']['value'];
if(!empty($search_value)){
$total_count = $this->db->query("SELECT employee_name,employee_email,employee_phone from users WHERE id like '%".$search_value."%' OR employee_name like '%".$search_value."%' OR employee_email like '%".$search_value."%' OR employee_phone like '%".$search_value."%'")->getResult();
$data = $this->$db->query("SELECT employee_name,employee_email,employee_phone from users WHERE id like '%".$search_value."%' OR employee_name like '%".$search_value."%' OR employee_email like '%".$search_value."%' OR employee_phone like '%".$search_value."%' limit $start, $length")->getResult();
}else{
// count all data
$total_count = $this->db->query("SELECT employee_name,employee_email,employee_phone from users")->getResult();
// get per page data
$data = $this->db->query("SELECT employee_name,employee_email,employee_phone from users limit $start, $length")->getResult();
}
$no = #$_POST['start'];
foreach ($data as $employee) {
$no++;
$row = array();
$row[] = $no;
$row[] = $employee->employee_name;
$row[] = $employee->employee_email;
$row[] = $employee->employee_phone;
$row[] ='<span class="role member">Update</span> || <span class="role admin">Delete</span>';
$data[] = $row;
}
$json_data = array(
"draw" => #$_POST['draw'],
"recordsTotal" => count($total_count),
"recordsFiltered" => count($total_count),
"data" => $data // total data array
);
echo json_encode($json_data);
}
<script>
var site_url = "<?php echo site_url(); ?>";
$(document).ready( function () {
$('#admin_user_datatable').DataTable({
paginationType: "full_numbers",
lengthMenu: [[5, 10, 15, 20], [5, 10, 15, 20]],
processing: true,
serverSide: true,
scrollY: "400px",
scrollCollapse: true,
ajax: {
url: site_url + "/ajax-datatable", // json datasource
type: "post",
data: {
// key1: value1 - in case if we want send data with request
}
},
columnDefs: [
{ orderable: false, targets: [0] }
],
bFilter: true, // to display datatable search
});
});
</script>