Example page in manual for Error Handling uses old/deprecated code

The example page for Error Handling uses deprecated method wddx_serialize_value and a callback method signature that does not match the current documentation recommendation:

• Callback signature in Example Page: function($errno, $errmsg, $filename, $linenum, $vars)
• Recommended callback signature in current documentation: handler( [int](https://www.php.net/manual/en/language.types.integer.php) $errno, [string](https://www.php.net/manual/en/language.types.string.php) $errstr, [string](https://www.php.net/manual/en/language.types.string.php) $errfile = ?, [int](https://www.php.net/manual/en/language.types.integer.php) $errline = ? ): [bool](https://www.php.net/manual/en/language.types.boolean.php)

The last parameter in example $vars maps to the old callback function parameter errcontext which has been removed in PHP8.0+

Start by locating the source for the linked Error Handling example page, then compare its callback signature and wddx_serialize_value usage with the current set-error-handler documentation. Done means the example no longer uses the deprecated function or removed errcontext parameter and matches the current callback recommendation.