Throw if product service can’t get element

src/services/ProductsService.php

@@ -230,12 +230,16 @@ private function _hasProductBeenSynced ($productId)
 	 * @return array
 	 * @throws SiteNotFoundException
 	 * @throws InvalidConfigException
+	 * @throws \Exception
 	 */
 	private function _buildProductData ($productId)
 	{
 		/** @var Element $product */
 		$product = Craft::$app->getElements()->getElementById($productId);
 
+		if (!$product)
+			throw new \Exception('Unable to find element with ID: ' . $productId);
+
 		// TODO: Tidy up all helper functions by getting and storing the correct
 		//  product and variant types, and using them later (rather that
 		//  re-checking in every function for every variant).