[2.x] Ensure void return type translates to null

Makefile

@@ -22,7 +22,7 @@ else
 		-v "`pwd`:`pwd`" \
 		-v "${COMPOSER_CACHE_DIR}:${COMPOSER_CONTAINER_CACHE_DIR}" \
 		-w "`pwd`" \
-		"ghcr.io/wyrihaximusnet/php:${PHP_VERSION}-nts-alpine${SLIM_DOCKER_IMAGE}-dev"
+		"ghcr.io/wyrihaximusnet/php:${PHP_VERSION}-zts-alpine${SLIM_DOCKER_IMAGE}-dev"
 endif
 
 ifneq (,$(findstring icrosoft,$(shell cat /proc/version)))

composer.json

@@ -1,6 +1,6 @@
 {
     "name": "react-parallel/contracts",
-    "description": "Interfaces for ReactPHP ext-parallel related packages",
+    "description": "\ud83d\udcdc Interfaces for ReactPHP ext-parallel related packages",
     "license": "MIT",
     "authors": [
         {
@@ -14,6 +14,8 @@
         "wyrihaximus/pool-info": "^2.0.0"
     },
     "require-dev": {
+        "ext-parallel": "*",
+        "react-parallel/stubs": "^1.2",
         "wyrihaximus/async-test-utilities": "^8.0.5"
     },
     "autoload": {
@@ -27,15 +29,23 @@
         }
     },
     "config": {
-        "platform": {
-            "php": "8.2.13"
-        },
-        "sort-packages": true,
         "allow-plugins": {
-            "infection/extension-installer": true,
             "dealerdirect/phpcodesniffer-composer-installer": true,
+            "ergebnis/composer-normalize": true,
             "icanhazstring/composer-unused": true,
-            "ergebnis/composer-normalize": true
-        }
+            "infection/extension-installer": true
+        },
+        "platform": {
+            "php": "8.2.13"
+        },
+        "sort-packages": true
+    },
+    "scripts": {
+        "post-install-cmd": [
+            "composer normalize"
+        ],
+        "post-update-cmd": [
+            "composer normalize"
+        ]
     }
 }