Don't allow null for loop

Author: WyriHaximus

src/Factory.php

@@ -18,7 +18,7 @@
 final class Factory
 {
     public static function create(
-        LoopInterface $loop = null,
+        LoopInterface $loop,
         array $options = []
     ): Client {
         return new Client(
@@ -49,7 +49,7 @@ private static function createContainer(LoopInterface $loop, array $options): Co
 
     private static function createTransport(
         ContainerInterface $container,
-        LoopInterface $loop = null,
+        LoopInterface $loop,
         array $options = []
     ): TransportClient {
         if (!isset($options[Options::TRANSPORT_OPTIONS])) {