Some readability improvments

Author: Juuso Leinonen

src/DataLoaderInterface.php

@@ -29,6 +29,7 @@ public function load($key);
      * @param array $keys
      *
      * @return Promise
+     * @throws \InvalidArgumentException
      */
     public function loadMany(array $keys);
 

src/DataLoaderOptions.php

@@ -100,7 +100,7 @@ private function validateCacheOption($shouldCache)
      */
     private function validateMaxBatchSizeOption($maxBatchSize)
     {
-        if ($maxBatchSize !== null && ! \is_int($maxBatchSize) || (int) $maxBatchSize < 0) {
+        if (($maxBatchSize !== null && ! \is_int($maxBatchSize)) || (int) $maxBatchSize < 0) {
             throw new \InvalidArgumentException('Expected argument $maxBatchSize to be null or a positive integer');
         }
     }