"Stripe Notice: Undefined property of Stripe\SubscriptionItem instance: quantity" swapping metered prices in subscriptions

[pietrantonio91]

• Cashier Version: 13.7.0
• Laravel Version: 8.73.2
• PHP Version: 7.4.27
• Database Driver & Version: MySQL 8

Description:

When swapping a subscripton price with a metered price it retrieve this notice:

Stripe Notice: Undefined property of Stripe\SubscriptionItem instance: quantity

I figured out this should be the problem line:

cashier-stripe/src/Subscription.php

Line 695 in 1a80ccb

'quantity' => $item->quantity,

As I've read in other issues and in docs metered prices must have "null" as quantity value.

So I solved this issue with a simple (similar to this issue):

'quantity' => $item->quantity ?? null

Here's my pull request.

Steps To Reproduce:

1. Create a subscription
2. $user->subscription()->swap('price_meteredPriceID');

[driesvints]

Thanks for the PR!