MAGETWO-58395: [Backport] An error occurs while saving configurable product - 2.1

Author: OlgaVasyltsun

app/code/Magento/ConfigurableProduct/Model/Product/VariationHandler.php

@@ -152,7 +152,7 @@ protected function fillSimpleProductData(
         \Magento\Catalog\Model\Product $parentProduct,
         $postData
     ) {
-        $typeId = isset($postData['weight']) && !empty($postData['weight'])
+        $typeId = !empty($postData['weight'])
             ? ProductType::TYPE_SIMPLE
             : ProductType::TYPE_VIRTUAL;