Update TopMenu.php

Function _columnBrake return null when limit is smaller then $total.
But _getHtml needs the result to be array.

Author: Krielkip

app/code/Magento/Theme/Block/Html/Topmenu.php

@@ -133,15 +133,15 @@ protected function _countItems($items)
      *
      * @param Menu $items
      * @param int $limit
-     * @return array|void
+     * @return array
      *
      * @todo: Add Depth Level limit, and better logic for columns
      */
     protected function _columnBrake($items, $limit)
     {
         $total = $this->_countItems($items);
         if ($total <= $limit) {
-            return;
+            return [];
         }
 
         $result[] = ['total' => $total, 'max' => (int)ceil($total / ceil($total / $limit))];