satellite: invalid coupon code returns 400 status code

fixes: #4782

Change-Id: Idcc00202ed91a10c280f706e14d4901bf2f61541

satellite/console/consoleweb/consoleapi/payments.go

@@ -16,6 +16,7 @@ import (
 	"go.uber.org/zap"
 
 	"storj.io/storj/satellite/console"
+	"storj.io/storj/satellite/payments/stripecoinpayments"
 )
 
 var (
@@ -278,6 +279,10 @@ func (p *Payments) ApplyCouponCode(w http.ResponseWriter, r *http.Request) {
 
 	coupon, err := p.service.Payments().ApplyCouponCode(ctx, couponCode)
 	if err != nil {
+		if stripecoinpayments.ErrInvalidCoupon.Has(err) {
+			p.serveJSONError(w, http.StatusBadRequest, err)
+			return
+		}
 		p.serveJSONError(w, http.StatusInternalServerError, err)
 		return
 	}

satellite/payments/stripecoinpayments/coupons.go

@@ -31,7 +31,7 @@ func (coupons *coupons) ApplyCouponCode(ctx context.Context, userID uuid.UUID, c
 		Code: stripe.String(couponCode),
 	})
 	if !promoCodeIter.Next() {
-		return nil, Error.New("Invalid coupon code")
+		return nil, ErrInvalidCoupon.New("Invalid coupon code")
 	}
 	promoCode := promoCodeIter.PromotionCode()
 

satellite/payments/stripecoinpayments/service.go

@@ -33,6 +33,9 @@ var (
 	// Error defines stripecoinpayments service error.
 	Error = errs.Class("stripecoinpayments service")
 
+	// ErrInvalidCoupon defines invalid coupon code error.
+	ErrInvalidCoupon = errs.Class("invalid coupon code")
+
 	mon = monkit.Package()
 )