Steps to reproduce the issue

Open the link
https://www.joom-dev.it/tgw/index.php?option=com_content&view=article&id=236&catid=38&Itemid=559
Click on the TOP / DOWN arrow

Expected result

Write a value on the database

Actual result

After migrating a Joomla 3 (PHP 7.4) website to Joomla 4.2.9 (PHP 8.2.1) this custom plugin stoppeod working.
It correctly reads values from the DB but it's unable to write new values.

System information (as much as possible)

Joomla version: 4.2.9
Php version: 8.2.1
Database version: 5.7.32-35

Additional comments

After migrating a Joomla 3 (PHP 7.4) website to Joomla 4.2.9 (PHP 8.2.1) I've stumbled upon this issue in a custom plugin.

obj = jQuery.parseJSON(response.data[0]);

The plugin stopped writing a filed in a database table.

The code is able to read and render values from the DB but it's not albe to write new values.

There must be some logic error in the PHP code itself, but I cannot figure this out.

I'm no PHP programmer and I really don't know how to adapt this PHP code to 8.2 / J4 version.

This is a sample live site with the error.
https://www.joom-dev.it/tgw/index.php?option=com_content&view=article&id=236&catid=38&Itemid=559

Code extract:

if(($user->guest == 0) || ($this->params->get("ccv_registerd_required", "true") == "false")) {
    $ajax = "
			function currentTime()
			{
			var now = new Date();
			return now.getHours() + now.getMinutes() + now.getSeconds();
			}

			function sendVote(id, action, request)
			{
			jQuery('.status').html('${loading}');
			" .
        /* request.data += '&stamp=' + currentTime() */
        " jQuery.ajax({
			type   : 'GET',
			data   : request,
			success: function (response) {
			" .
        /* console.log(response.data[0]); */
        " obj = jQuery.parseJSON(response.data[0]);
			" .
        /*
        console.log(obj);
        console.log(obj['likes']);
        console.log(obj['unlikes']);
        */
        " jQuery('#cLike-{$art_id}').html(' ' + obj['pct_likes'] + ' %');
			jQuery('#cUnlike-{$art_id}').html(' ' + obj['pct_unlikes'] + ' %');
			jQuery('.status').html(obj['message']);
			},
			error: function(response) {
			obj = jQuery.parseJSON(response.responseText);
			var data2 = 'err: ';
			for(key in obj)
			{
			data2 = data2 + ' ' + obj[key] + '<br/>';
			}
			jQuery('.status').html(data2);
			}
			});
			}

			jQuery(document).ready( function() {
			jQuery('.like img').on( 'click', function(event) {
			var request = {
			'option' : 'com_ajax',
			'plugin' : 'ccvote',
			'group'  : 'content',
			'cmd'    : 'like',
			'data'   : { id: {$art_id} },
			'art_id' : '{$art_id}',
			'user_id': '{$user->id}',
			'user_name': '{$user->username}',
			'format' : '{$format}'
			};
			sendVote( {$art_id}, 'like', request);
			});
			jQuery('.unlike img').on( 'click', function(event) {
			var request = {
			'option' : 'com_ajax',
			'plugin' : 'ccvote',
			'group'  : 'content',
			'cmd'    : 'unlike',
			'data'   : { id: {$art_id} },
			'art_id' : '{$art_id}',
			'user_id': '{$user->id}',
			'user_name': '{$user->username}',
			'format' : '{$format}'
			};
			sendVote( {$art_id}, 'unlike', request);
			});
			});
			";
} else {
    $ajax = "
			var msg = '<b>You must be logged in to vote.</b>';
			jQuery(document).ready( function() {
			jQuery('.like img').on( 'click', function(event) {
			jQuery('.status').html(msg);
			});
			jQuery('.unlike img').on( 'click', function(event) {
			jQuery('.status').html(msg);
			});
			});
			";
}

How can I do to fix the PHP code to allow the correct addition of new fileds or values?

This is the error log from the console "console.log(response.data[0]);"

PHP Warning: Attempt to read property "id" on null in /web/htdocs/www.joom-dev.it/home/tgw/libraries/src/Updater/Adapter/ExtensionAdapter.php on line 303"

Line 303 below:

$this->latest->client_id = ApplicationHelper::getClientInfo($this->latest->client, true)->id;