Fix some PointOfSaleAggregateModel memory leaks (#15055)

Author: staskus

Hardware/Hardware/CardReader/StripeCardReader/StripeCardReaderService.swift

@@ -430,7 +430,13 @@ extension StripeCardReaderService: CardReaderService {
             }
 
             paymentCancellable.cancel({ [weak self] error in
-                if error == nil {
+                // If the action could not be canceled,
+                // e.g. it has already completed, the completion block will be called with an
+                // error. Otherwise, the completion block will be called with nil.
+                if let error {
+                    let underlyingError = Self.logAndDecodeError(error)
+                    promise(.failure(CardReaderServiceError.paymentCancellation(underlyingError: underlyingError)))
+                } else {
                     self?.paymentCancellable = nil
                     cancelPaymentIntent()
                 }

WooCommerce/Classes/POS/Card Present Payments/CardPresentPaymentService.swift

@@ -108,6 +108,7 @@ final class CardPresentPaymentService: CardPresentPaymentFacade {
             DDLogError("Attempting to cancel the payment has failed \(error)")
         }
 
+        paymentTask?.cancel()
         connectionControllerManager.knownReaderProvider.forgetCardReader()
 
         return await withCheckedContinuation { continuation in

WooCommerce/Classes/POS/Models/PointOfSaleAggregateModel.swift

@@ -184,7 +184,7 @@ extension PointOfSaleAggregateModel {
                     }
                 }
                 .removeDuplicates()
-                .sink { _ in
+                .sink { [weak self] _ in
                     Task { @MainActor [weak self] in
                         await self?.collectCardPayment()
                     }