Make nullable parameter types explicit

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Change Log
 
+## 1.3.1 - unreleased
+
+- Made nullable parameter types explicit (PHP 8.4 compatibility)
+
 ## 1.3.0 - 2024-01-04
 
 ### Fixed

src/FulfilledPromise.php

@@ -22,7 +22,7 @@ public function __construct($result)
         $this->result = $result;
     }
 
-    public function then(callable $onFulfilled = null, callable $onRejected = null)
+    public function then(?callable $onFulfilled = null, ?callable $onRejected = null)
     {
         if (null === $onFulfilled) {
             return $this;

src/Promise.php

@@ -41,7 +41,7 @@ interface Promise
      *
      * @return Promise a new resolved promise with value of the executed callback (onFulfilled / onRejected)
      */
-    public function then(callable $onFulfilled = null, callable $onRejected = null);
+    public function then(?callable $onFulfilled = null, ?callable $onRejected = null);
 
     /**
      * Returns the state of the promise, one of PENDING, FULFILLED or REJECTED.

src/RejectedPromise.php

@@ -19,7 +19,7 @@ public function __construct(\Throwable $exception)
         $this->exception = $exception;
     }
 
-    public function then(callable $onFulfilled = null, callable $onRejected = null)
+    public function then(?callable $onFulfilled = null, ?callable $onRejected = null)
     {
         if (null === $onRejected) {
             return $this;