Assert class instances of collection items

modules/opd_podcast/src/Guests.php

@@ -4,6 +4,9 @@ declare(strict_types=1);
 
 namespace Drupal\opd_podcast;
 
+use Webmozart\Assert\Assert;
+
+
 /**
  * @implements \IteratorAggregate<Guest>
  */
@@ -13,6 +16,7 @@ final class Guests implements \Countable, \IteratorAggregate, \Stringable {
   * @param Guest[] $guests
   */
   private function __construct(private array $guests) {
+    Assert::allIsInstanceOf($guests, Guest::class);
   }
 
   public function count(): int {