Handle fatal errors when subscription plugin gets deactivated due to …

…outdated version (#10416)

changelog/fix-5623-handle-fatal-errors-on-wc-subscriptions-deactivated-due-outdated-version

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fix
+
+Prevent fatal errors when subscription is deactivated due outdated version.

includes/compat/subscriptions/trait-wc-payments-subscriptions-utilities.php

@@ -69,6 +69,9 @@ public function is_payment_recurring( $order_id ) {
 	 * @return bool Indicates whether the save payment method checkbox should be displayed or not.
 	 */
 	public function display_save_payment_method_checkbox( $display ) {
+		if ( ! class_exists( 'WC_Subscriptions_Cart' ) ) {
+			return false;
+		}
 		if ( WC_Subscriptions_Cart::cart_contains_subscription() || $this->is_changing_payment_method_for_subscription() ) {
 			return false;
 		}
@@ -83,7 +86,7 @@ public function display_save_payment_method_checkbox( $display ) {
 	 * @return bool
 	 */
 	public function is_subscription_item_in_cart() {
-		if ( $this->is_subscriptions_enabled() ) {
+		if ( class_exists( 'WC_Subscriptions_Cart' ) && $this->is_subscriptions_enabled() ) {
 			return WC_Subscriptions_Cart::cart_contains_subscription() || $this->cart_contains_renewal();
 		}
 		return false;

includes/subscriptions/class-wc-payments-product-service.php

@@ -459,7 +459,7 @@ public function archive_price( string $wcpay_price_id, $test_mode = null ) {
 	 * @param int $product_id ID of the product that's being saved.
 	 */
 	public function limit_subscription_product_intervals( $product_id ) {
-		if ( $this->is_subscriptions_plugin_active() ) {
+		if ( $this->is_subscriptions_plugin_active() || ! class_exists( 'WC_Subscriptions_Product' ) ) {
 			return;
 		}
 
@@ -500,7 +500,7 @@ public function limit_subscription_product_intervals( $product_id ) {
 	 * @param int $index Variation index in the incoming array.
 	 */
 	public function limit_subscription_variation_intervals( $product_id, $index ) {
-		if ( $this->is_subscriptions_plugin_active() ) {
+		if ( $this->is_subscriptions_plugin_active() || ! class_exists( 'WC_Subscriptions_Product' ) ) {
 			return;
 		}
 
@@ -793,6 +793,10 @@ public function get_wcpay_price_id( WC_Product $product, $test_mode = null ): st
 		wc_deprecated_function( __FUNCTION__, '3.3.0' );
 		$price_id = $product->get_meta( self::get_wcpay_price_id_option( $test_mode ), true );
 
+		if ( ! class_exists( 'WC_Subscriptions_Product' ) ) {
+			return $price_id;
+		}
+
 		// If the subscription product doesn't have a WC Pay price ID, create one now.
 		if ( empty( $price_id ) && WC_Subscriptions_Product::is_subscription( $product ) ) {
 			$is_current_environment = null === $test_mode || WC_Payments::mode()->is_test() === $test_mode;