Online PHP editor | output for fnDPQ

<?php class Coalescing { protected $attributes = [ 'attribute1' => 'value1', ]; public function __get($name) { print "GET\n"; if (array_key_exists($name, $this->attributes)) { return $this->attributes[$name]; } trigger_error("Property $name does not exist"); return null; } public function __isset($name) { print "ISSET\n"; return array_key_exists($name, $this->attributes); } } $coal = new Coalescing(); version_compare(PHP_VERSION, "7.0", ">=") && eval('var_dump($coal->attribute1 ?? "default");'); //GET //string(6) "value1" version_compare(PHP_VERSION, "7.0", ">=") && eval('var_dump($coal->attribute2 ?? "default");'); //GET //PHP Notice: Property attribute2 does not exist in /var/www/html/test.php on line 23 //PHP Stack trace: //PHP 1. {main}() /var/www/html/test.php:0 //PHP 2. Coalescing->__get() /var/www/html/test.php:41 //PHP 3. trigger_error() /var/www/html/test.php:23 ///var/www/html/test.php:41: //string(7) "default"