fix: return billing period for free phases too (#3391)

Author: GAlexIHU

openmeter/productcatalog/subscription/http/mapping.go

@@ -393,16 +393,13 @@ func MapSubscriptionViewToAPI(view subscription.SubscriptionView) (api.Subscript
 		BillablesMustAlign: lo.ToPtr(true), // this field is deprecated on API, we'll get rid of it eventually
 	}
 
-	if currPhase, ok := view.Spec.GetCurrentPhaseAt(clock.Now()); ok && currPhase.HasBillables() {
+	{
 		period, err := view.Spec.GetAlignedBillingPeriodAt(clock.Now())
 		if err != nil {
-			// GetAlignedBillingPeriodAt cannot be calculated for all aligned subscriptions.
-			if _, ok := lo.ErrorsAs[subscription.NoBillingPeriodError](err); !ok {
+			if !subscription.IsErrSubscriptionBillingPeriodQueriedBeforeSubscriptionStart(err) {
 				return api.SubscriptionExpanded{}, err
 			}
-		}
-
-		if err == nil {
+		} else {
 			alg.CurrentAlignedBillingPeriod = &api.Period{
 				From: period.From,
 				To:   period.To,

openmeter/subscription/errors.go

@@ -24,6 +24,10 @@ func NewErrSubscriptionBillingPeriodQueriedBeforeSubscriptionStart(queriedAt, su
 	return ErrSubscriptionBillingPeriodQueriedBeforeSubscriptionStart.WithAttr("queried_at", queriedAt).WithAttr("subscription_start", subscriptionStart)
 }
 
+func IsErrSubscriptionBillingPeriodQueriedBeforeSubscriptionStart(err error) bool {
+	return IsValidationIssueWithCode(err, ErrCodeSubscriptionBillingPeriodQueriedBeforeSubscriptionStart)
+}
+
 // TODO(galexi): "ValidationIssue" is not the right concept here. We should have a different kind of error with all this capability. It's used here as a hack to localize things for the time being.
 
 func IsValidationIssueWithCode(err error, code models.ErrorCode) bool {

openmeter/subscription/subscriptionspec.go

@@ -1153,16 +1153,3 @@ func (e AlignmentError) Error() string {
 func (e AlignmentError) Unwrap() error {
 	return e.Inner
 }
-
-// NoBillingPeriodError is an error that occurs when a phase has no billing period.
-type NoBillingPeriodError struct {
-	Inner error
-}
-
-func (e NoBillingPeriodError) Error() string {
-	return fmt.Sprintf("no billing period: %s", e.Inner)
-}
-
-func (e NoBillingPeriodError) Unwrap() error {
-	return e.Inner
-}

openmeter/subscription/workflow/errors.go

@@ -16,8 +16,6 @@ func MapSubscriptionErrors(err error) error {
 		return models.NewGenericValidationError(sErr)
 	} else if sErr, ok := lo.ErrorsAs[*subscription.AlignmentError](err); ok {
 		return models.NewGenericConflictError(sErr)
-	} else if sErr, ok := lo.ErrorsAs[*subscription.NoBillingPeriodError](err); ok {
-		return models.NewGenericValidationError(sErr)
 	}
 
 	return err