Use return null; when the return type is null

Author: wouterj

src/Illuminate/Container/Util.php

@@ -53,7 +53,7 @@ public static function getParameterClassName($parameter)
         $type = $parameter->getType();
 
         if (! $type instanceof ReflectionNamedType || $type->isBuiltin()) {
-            return;
+            return null;
         }
 
         $name = $type->getName();

src/Illuminate/Translation/MessageSelector.php

@@ -61,7 +61,7 @@ private function extractFromString($part, $number)
         preg_match('/^[\{\[]([^\[\]\{\}]*)[\}\]](.*)/s', $part, $matches);
 
         if (count($matches) !== 3) {
-            return;
+            return null;
         }
 
         $condition = $matches[1];