diff --git a/lib/Doctrine/ORM/Event/ListenersInvoker.php b/lib/Doctrine/ORM/Event/ListenersInvoker.php
index dacf0dcea31..d0ea7cfb250 100644
--- a/lib/Doctrine/ORM/Event/ListenersInvoker.php
+++ b/lib/Doctrine/ORM/Event/ListenersInvoker.php
@@ -15,20 +15,16 @@
  */
 class ListenersInvoker
 {
-    public const INVOKE_NONE      = 0;
-    public const INVOKE_LISTENERS = 1;
-    public const INVOKE_CALLBACKS = 2;
-    public const INVOKE_MANAGER   = 4;
+    final public const INVOKE_NONE      = 0;
+    final public const INVOKE_LISTENERS = 1;
+    final public const INVOKE_CALLBACKS = 2;
+    final public const INVOKE_MANAGER   = 4;
 
-    /** @var EntityListenerResolver The Entity listener resolver. */
-    private $resolver;
+    /** The Entity listener resolver. */
+    private readonly EntityListenerResolver $resolver;
 
-    /**
-     * The EventManager used for dispatching events.
-     *
-     * @var EventManager
-     */
-    private $eventManager;
+    /** The EventManager used for dispatching events. */
+    private readonly EventManager $eventManager;
 
     public function __construct(EntityManagerInterface $em)
     {
@@ -42,10 +38,9 @@ public function __construct(EntityManagerInterface $em)
      * @param ClassMetadata $metadata  The entity metadata.
      * @param string        $eventName The entity lifecycle event.
      *
-     * @return int Bitmask of subscribed event systems.
-     * @psalm-return int-mask-of<self::INVOKE_*>
+     * @psalm-return int-mask-of<self::INVOKE_*> Bitmask of subscribed event systems.
      */
-    public function getSubscribedSystems(ClassMetadata $metadata, $eventName)
+    public function getSubscribedSystems(ClassMetadata $metadata, string $eventName): int
     {
         $invoke = self::INVOKE_NONE;
 
@@ -71,13 +66,15 @@ public function getSubscribedSystems(ClassMetadata $metadata, $eventName)
      * @param string        $eventName The entity lifecycle event.
      * @param object        $entity    The Entity on which the event occurred.
      * @param EventArgs     $event     The Event args.
-     * @param int           $invoke    Bitmask to invoke listeners.
-     * @psalm-param int-mask-of<self::INVOKE_*> $invoke
-     *
-     * @return void
+     * @psalm-param int-mask-of<self::INVOKE_*> $invoke Bitmask to invoke listeners.
      */
-    public function invoke(ClassMetadata $metadata, $eventName, $entity, EventArgs $event, $invoke)
-    {
+    public function invoke(
+        ClassMetadata $metadata,
+        string $eventName,
+        object $entity,
+        EventArgs $event,
+        int $invoke
+    ): void {
         if ($invoke & self::INVOKE_CALLBACKS) {
             foreach ($metadata->lifecycleCallbacks[$eventName] as $callback) {
                 $entity->$callback($event);
diff --git a/lib/Doctrine/ORM/Mapping/DefaultEntityListenerResolver.php b/lib/Doctrine/ORM/Mapping/DefaultEntityListenerResolver.php
index e89263d83c8..fbe3118155e 100644
--- a/lib/Doctrine/ORM/Mapping/DefaultEntityListenerResolver.php
+++ b/lib/Doctrine/ORM/Mapping/DefaultEntityListenerResolver.php
@@ -4,12 +4,7 @@
 
 namespace Doctrine\ORM\Mapping;
 
-use InvalidArgumentException;
-
 use function get_class;
-use function gettype;
-use function is_object;
-use function sprintf;
 use function trim;
 
 /**
@@ -18,12 +13,9 @@
 class DefaultEntityListenerResolver implements EntityListenerResolver
 {
     /** @psalm-var array<class-string, object> Map to store entity listener instances. */
-    private $instances = [];
+    private array $instances = [];
 
-    /**
-     * {@inheritdoc}
-     */
-    public function clear($className = null)
+    public function clear(?string $className = null): void
     {
         if ($className === null) {
             $this->instances = [];
@@ -32,33 +24,18 @@ public function clear($className = null)
         }
 
         $className = trim($className, '\\');
-        if (isset($this->instances[$className])) {
-            unset($this->instances[$className]);
-        }
+        unset($this->instances[$className]);
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function register($object)
+    public function register(object $object): void
     {
-        if (! is_object($object)) {
-            throw new InvalidArgumentException(sprintf('An object was expected, but got "%s".', gettype($object)));
-        }
-
         $this->instances[get_class($object)] = $object;
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function resolve($className)
+    public function resolve(string $className): object
     {
         $className = trim($className, '\\');
-        if (isset($this->instances[$className])) {
-            return $this->instances[$className];
-        }
 
-        return $this->instances[$className] = new $className();
+        return $this->instances[$className] ??= new $className();
     }
 }
diff --git a/lib/Doctrine/ORM/Mapping/EntityListenerResolver.php b/lib/Doctrine/ORM/Mapping/EntityListenerResolver.php
index 2a10a2f9fa2..7cfed783876 100644
--- a/lib/Doctrine/ORM/Mapping/EntityListenerResolver.php
+++ b/lib/Doctrine/ORM/Mapping/EntityListenerResolver.php
@@ -13,26 +13,18 @@ interface EntityListenerResolver
      * Clear all instances from the set, or a specific instance when given its identifier.
      *
      * @param string|null $className May be any arbitrary string. Name kept for BC only.
-     *
-     * @return void
      */
-    public function clear($className = null);
+    public function clear(?string $className = null): void;
 
     /**
      * Returns a entity listener instance for the given identifier.
      *
      * @param string $className May be any arbitrary string. Name kept for BC only.
-     *
-     * @return object An entity listener
      */
-    public function resolve($className);
+    public function resolve(string $className): object;
 
     /**
      * Register a entity listener instance.
-     *
-     * @param object $object An entity listener
-     *
-     * @return void
      */
-    public function register($object);
+    public function register(object $object): void;
 }
diff --git a/psalm-baseline.xml b/psalm-baseline.xml
index 921f32178d7..158d6575ce5 100644
--- a/psalm-baseline.xml
+++ b/psalm-baseline.xml
@@ -503,9 +503,6 @@
     </MissingConstructor>
   </file>
   <file src="lib/Doctrine/ORM/Mapping/DefaultEntityListenerResolver.php">
-    <DocblockTypeContradiction occurrences="1">
-      <code>is_object($object)</code>
-    </DocblockTypeContradiction>
     <InvalidStringClass occurrences="1">
       <code>new $className()</code>
     </InvalidStringClass>
diff --git a/tests/Doctrine/Tests/ORM/Mapping/EntityListenerResolverTest.php b/tests/Doctrine/Tests/ORM/Mapping/EntityListenerResolverTest.php
index f1e20934feb..64af718f92a 100644
--- a/tests/Doctrine/Tests/ORM/Mapping/EntityListenerResolverTest.php
+++ b/tests/Doctrine/Tests/ORM/Mapping/EntityListenerResolverTest.php
@@ -87,11 +87,4 @@ public function testClearAll(): void
         self::assertNotSame($obj1, $this->resolver->resolve($className1));
         self::assertNotSame($obj2, $this->resolver->resolve($className2));
     }
-
-    public function testRegisterStringException(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        $this->expectExceptionMessage('An object was expected, but got "string".');
-        $this->resolver->register('CompanyContractListener');
-    }
 }