[php-src] Issue #24743: var_export does not handle exception correctly when retrieving object

Issue: https://github.com/php/php-src/issues/24743 Author: Sjord ### Description In ext/standard/var.c the return value of php_object_element_export is not checked. If retrieving an object property throws an exception, var_export outputs a partial export. I would expect no output and only an exception. ``` --TEST-- var_export(): exception from a nested object's property hook must abort the export --FILE-- <?php class Inner { public static bool $fail = true; public int $x = 1 { get { if (self::$fail) { throw new Exception("hook failed"); } return $this->x; } } } class Outer { public Inner $a; public int $b = 2; public function __construct() { $this->a = new Inner; } } $o = new Outer; function show_export(string $label, callable $export): void { ob_start(); $caught = null; try { $export(); } catch (Throwable $e) { $caught = $e; } $output = ob_get_clean(); echo "--- ", $label, " ---\n"; if ($caught === null) { echo "No exception\n"; } else { echo "Caught: ", $caught->getMessage(), "\n"; } if ($output !== '') { echo "BUG: var_export() emitted partial output before the exception:\n"; echo $output, "\n"; echo "--- end of partial output ---\n"; } } show_export("print mode, nested object", fn() => var_export($o)); show_export("return mode, nested object", fn() => var_export($o, true)); show_export("print mode, object inside array", fn() => var_export([1, $o])); echo "--- recovery: recursion guards were released ---\n"; Inner::$fail = false; var_export($o); echo "\n"; ?> --EXPECT-- --- print mode, nested object --- Caught: hook failed --- return mode, nested object --- Caught: hook failed --- print mode, object inside array --- Caught: hook failed --- recovery: recursion guards were released --- \Outer::__set_state(array( 'a' => \Inner::__set_state(array( 'x' => 1, )), 'b' => 2, )) ``` ### PHP Version ```plain PHP 8.4 branch and PHP master branch ``` ### Operating System _No response_