Make sure that we have arrays inside the for loop checking for multip…

…le dimensions

src/Collection/CollectionTrait.php

@@ -696,7 +696,7 @@ public function cartesianProduct(callable $operation = null, callable $filter =
         $collectionArraysKeys = [];
         $collectionArraysCounts = [];
 
-        foreach ($this as $value) {
+        foreach ($this->toList() as $value) {
             if (count($value) !== count($value, COUNT_RECURSIVE)) {
                 throw new LogicException('Cannot find the cartesian product of a multidimensional array');
             }