Fix compat with WC vendors and product variations (variations do not have any...

Fix compat with WC vendors and product variations (variations do not have any post_author, so we need to use the parent product in this case...

includes/rules_shipping_framework_woocommerce.php

@@ -234,7 +234,14 @@ class RulesShippingFrameworkWooCommerce extends RulesShippingFramework {
 		if (class_exists("WC_Vendors")) {
 			$vendorids = array();
 			foreach ($products as $product) {
-				$vendorids[] = $product['data']->post->post_author;
+				// Variations inherit the vendor from their parent product 
+				if (!isset($product['variation_id'])) {
+					// "Normal" product, not a variation
+					$vendorids[] = $product['data']->post->post_author;
+				} else {
+					// A variation => load the parent product instead and use its vendor
+					$vendorids[] = get_post_field('post_author', $product['product_id']);
+				}
 			}
 			$data['vendorids'] = array_unique($vendorids);