MAGETWO-57312: [GITHUB] Notice: Undefined offset: 0 in Order\Config.php

- conflict merge

Author: Oleksandr Dubovyk

app/code/Magento/Sales/Model/Order/Config.php

@@ -250,10 +250,11 @@ public function getInvisibleOnFrontStatuses()
      */
     protected function _getStatuses($visibility)
     {
-        if ($this->statuses === null) {
-            
-            $this->statuses = [ true => [], false => [] ];
-            
+        if ($this->statuses == null) {
+            $this->statuses = [
+                true => [],
+                false => [],
+            ];
             foreach ($this->_getCollection() as $item) {
                 $visible = (bool) $item->getData('visible_on_front');
                 $this->statuses[$visible][] = $item->getData('status');