fix: redirect user to legacy checkout when voucher is invalid for leg…

…acysystem

ecommerce/coupons/views.py

@@ -173,7 +173,10 @@ def get(self, request):  # pylint: disable=too-many-statements
             voucher = Voucher.objects.get(code=code)
         except Voucher.DoesNotExist:
             msg = 'No voucher found with code {code}'.format(code=code)
-            return render(request, template_name, {'error': _(msg)})
+            messages.warning(self.request, _(msg))
+            redirect_url = get_payment_microfrontend_or_basket_url(self.request) + "?coupon_redeem_redirect=1"
+            redirect_url = add_stripe_flag_to_url(redirect_url, self.request)
+            return HttpResponseRedirect(redirect_url)
 
         try:
             product = StockRecord.objects.get(partner_sku=sku).product