[php-src] Issue #23061: SessionHandler::create_sid() callback failure leaks memory in debug build

Issue: https://github.com/php/php-src/issues/23061
Author: arshidkv12

### Description

The following code:

```php
<?php
class a extends SessionHandler {
     
    function create_sid(): string {
    
        return [3,6];
        
    }
}
$c = new a;
session_set_save_handler($c);
session_start();
```

## Actual result

A TypeError is thrown, but the debug build also reports memory leaks, for example:

`=== Total 2 memory leaks detected ===`

The leaks originate from allocations made by the files session handler (ps_files and its basedir string).

 


### PHP Version

```plain
PHP 8.6.0-dev (cli) (built: Aug  5 2026 15:03:24) (NTS DEBUG)
Copyright © The PHP Group and Contributors
Zend Engine v4.6.0-dev, Copyright © Zend by Perforce
    with Zend OPcache v8.6.0-dev, Copyright ©, by Zend by Perforce
```

### Operating System

_No response_