fix

core/tests/Drupal/Tests/Core/EventSubscriber/RedirectResponseSubscriberTest.php

@@ -48,8 +48,8 @@ class RedirectResponseSubscriberTest extends UnitTestCase {
   protected function setUp(): void {
     parent::setUp();
 
-    $this->loggerClosure = function () {
-      $this->prophesize(LoggerInterface::class)->reveal();
+    $this->loggerClosure = function (): LoggerInterface {
+      return $this->prophesize(LoggerInterface::class)->reveal();
     };
 
     $this->requestContext = $this->getMockBuilder('Drupal\Core\Routing\RequestContext')