fix possible nullable item api responses to just return an empty array item list (#181)

* fix possible nullable item api responses to just return an empty array item list

Author: Alexandru Bucur

src/MessageBird/Resources/Base.php

@@ -168,13 +168,20 @@ public function getList(?array $parameters = [])
 
             $objectName = $this->object;
 
+            $baseList->items = [];
+
+            if ($items === null) {
+                return $baseList;
+            }
+
             foreach ($items as $item) {
                 /** @psalm-suppress UndefinedClass */
                 $object = new $objectName($this->httpClient);
 
                 $message = $object->loadFromArray($item);
                 $baseList->items[] = $message;
             }
+
             return $baseList;
         }