fix: invoice event unmarshaling

We need to remove the invoice.Workflow.Apps member as it's not json serializable.

Either ways, the apps service should be used in workers to acquire
an up-to-date app based on the payload.Workflow.AppReferences

openmeter/billing/events.go

@@ -8,12 +8,26 @@ const (
 	EventSubsystem metadata.EventSubsystem = "billing"
 )
 
+type EventInvoice Invoice
+
+func NewEventInvoice(invoice Invoice) EventInvoice {
+	// This causes a stack overflow
+	payload := invoice.RemoveCircularReferences()
+
+	// Remove the Apps from the payload, as they are not json unmarshallable
+	// but either ways, the apps service should be used in workers to acquire
+	// an up-to-date app based on the payload.Workflow.AppReferences
+	payload.Workflow.Apps = nil
+
+	return EventInvoice(payload)
+}
+
 type InvoiceCreatedEvent struct {
-	Invoice `json:",inline"`
+	EventInvoice `json:",inline"`
 }
 
 func NewInvoiceCreatedEvent(invoice Invoice) InvoiceCreatedEvent {
-	return InvoiceCreatedEvent{invoice.RemoveCircularReferences()}
+	return InvoiceCreatedEvent{NewEventInvoice(invoice)}
 }
 
 func (e InvoiceCreatedEvent) EventName() string {
@@ -32,5 +46,5 @@ func (e InvoiceCreatedEvent) EventMetadata() metadata.EventMetadata {
 }
 
 func (e InvoiceCreatedEvent) Validate() error {
-	return e.Invoice.Validate()
+	return e.EventInvoice.Validate()
 }

openmeter/billing/worker/subscription/sync.go

@@ -836,7 +836,7 @@ func (h *Handler) cloneLineForUpsert(line *billing.Line) *billing.Line {
 
 // HandleInvoiceCreation is a handler for the invoice creation event, it will make sure that
 // we are backfilling the items consumed by invoice creation into the gathering invoice.
-func (h *Handler) HandleInvoiceCreation(ctx context.Context, invoice billing.Invoice) error {
+func (h *Handler) HandleInvoiceCreation(ctx context.Context, invoice billing.EventInvoice) error {
 	if invoice.Status == billing.InvoiceStatusGathering {
 		return nil
 	}

openmeter/billing/worker/worker.go

@@ -130,7 +130,7 @@ func (w *Worker) eventHandler(opts WorkerOptions) (message.NoPublishHandlerFunc,
 			return w.subscriptionHandler.SyncronizeSubscription(ctx, event.UpdatedView, time.Now())
 		}),
 		grouphandler.NewGroupEventHandler(func(ctx context.Context, event *billing.InvoiceCreatedEvent) error {
-			return w.subscriptionHandler.HandleInvoiceCreation(ctx, event.Invoice)
+			return w.subscriptionHandler.HandleInvoiceCreation(ctx, event.EventInvoice)
 		}),
 	)
 	if err != nil {