Add is_array to the countable check should a plain array be the res…

…ult.

src/Http/Resources/BaseApiResource.php

@@ -165,7 +165,7 @@ protected function relationships()
             }
 
             $data = $this->resource->$relationship;
-            if ($data instanceof Countable && 0 == count($data)) {
+            if ((is_array($data) || $data instanceof \Countable) && 0 == count($data)) {
                 continue;
             }