Problem downloading products from M1.9.3.6 Export/Entity/Product.php on line 947

I’m trying to download my products from Magento 1.9.3.6 and I keep getting an error:

Fatal error: Unsupported operand types in public_html/app/code/core/Mage/ImportExport/Model/Export/Entity/Product.php on line 947

I’ve tried to research this and did find a website that mention to replace the line 947 with the following:

$dataRow += $stockItemRows[$productId];
if (isset($stockItemRows[$productId])) {
$dataRow = array_merge($dataRow, $stockItemRows[$productId]);
}

But it doesn’t seem to work.