I have warning and notice on opencart site. Please give me suggest what to do…

Warning: array_keys() expects parameter 1 to be array, string given in :

$k = array_keys($data);

Notice: Trying to access array offset on value of type null in:

$k = preg_replace_callback('/[[0-9]+/', function($match){return '';}, $k[0]);

After saving data It show two block windows insted one + warnings:

image 01 image 02 image 03

Illegal string offset ‘slider_id’ , ‘layout_id’ , ‘position’ , ‘status’ , ‘sort_order’ in:

<?php if($allslide['id'] == $module_data['slider_id']){ ?>
<?php if($layout['layout_id'] == $module_data['layout_id']){ ?>
if($module_data['position'] == $getpos){ ?>
<?php if($module_data['status'] == 0){ ?>
<?php if($module_data['status'] == 1){ ?>
<td class="right"><input type="text" name="revslideropencart_module[<?php echo $module_row; ?>][sort_order]" value="<?php echo $module_data['sort_order'] ?>" size="3" />

Code:

case "add_slider_pos_val":
//$data = array();
$newdata = array();
if(!empty($data)){
    $k = array_keys($data);
    $k = preg_replace_callback('/[[0-9]+/', function($match){return '';}, $k[0]);
    if(is_array($data)) foreach($data as $key => $arr){
        $newdata[$k][] = $arr;
    }
    $data = $newdata;
}
sdsconfig::editSetting('revslider',$data);
self::ajaxResponseSuccess(__("Slider Position Save SuccessFully", 'revslider'));
break;

If put:

$data = array();

All warnings disappeare but do not showing data block windows.

If put [0] in:

$newdata[$k][0] = $arr;

Can add only one data window block and it is always disabled. And no possible change the settings.