Merge branch 'v3' into v4

# Conflicts:
#	CHANGELOG.md

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Release Notes for Stripe for Craft Commerce
 
+## Unreleased
+
+- Fixed a PHP error that could occur when handling a webhook request. ([#294](https://github.com/craftcms/commerce-stripe/issues/294))
+
 ## 4.1.2.1 - 2024-03-28
 
 - Fixed a bug where floating point rounding precision could cause payments/refunds to fail. ([#296](https://github.com/craftcms/commerce-stripe/pull/296))
@@ -59,6 +63,11 @@
 - Deprecated creating new payment sources via the `commerce/subscriptions/subscribe` action.
 - Fixed a bug where `craft\commerce\stripe\base\SubscriptionGateway::getSubscriptionPlans()` was returning incorrectly-formatted data.
 
+## 3.1.2 - 2024-04-09
+
+- Fixed a PHP error that could occur when handling a webhook request. ([#294](https://github.com/craftcms/commerce-stripe/issues/294))
+- Plans’ data is now updated when the associated plan is updated in Stripe. ([#240](https://github.com/craftcms/commerce-stripe/issues/240))
+
 ## 3.1.1 - 2023-05-10
 
 - Stripe customers’ default payment methods are now kept in sync with Craft users’ primary payment sources. ([#235](https://github.com/craftcms/commerce-stripe/issues/235))

src/base/SubscriptionGateway.php

@@ -867,7 +867,9 @@ protected function handleInvoiceCreated(array $data): void
             ]));
         }
 
-        $canBePaid = empty($stripeInvoice['paid']) && $stripeInvoice['billing'] === 'charge_automatically';
+        $stripeInvoiceBilling = isset($stripeInvoice['billing']) && $stripeInvoice['billing'] ? $stripeInvoice['billing'] : null;
+
+        $canBePaid = empty($stripeInvoice['paid']) && $stripeInvoiceBilling === 'charge_automatically';
 
         if (StripePlugin::getInstance()->getSettings()->chargeInvoicesImmediately && $canBePaid) {
             $invoice = $this->getStripeClient()->invoices->retrieve($stripeInvoice['id']);