Fix trim of order number based on order number template (#3)

* Fix reference when order number template ends with or contains {0}

src/Umbraco.Commerce.PaymentProviders.Quickpay/Api/QuickpayClient.cs

@@ -98,6 +98,10 @@ private async Task<TResult> RequestAsync<TResult>(string url, Func<IFlurlRequest
             {
                 throw;
             }
+            catch (Exception ex)
+            {
+                throw;
+            }
 
             return result;
         }

src/Umbraco.Commerce.PaymentProviders.Quickpay/QuickpayCheckoutPaymentProvider.cs

@@ -98,12 +98,12 @@ public override async Task<PaymentFormResult> GenerateFormAsync(PaymentProviderC
                             else if (orderNumberTemplate.EndsWith("{0}"))
                             {
                                 // Trim prefix
-                                reference = reference.Substring(prefix.Length - 1);
+                                reference = reference.Substring(prefix.Length);
                             }
                             else if (orderNumberTemplate.Contains("{0}"))
                             {
                                 // Trim prefix & suffix
-                                reference = reference.Substring(prefix.Length - 1, reference.Length - suffix.Length);
+                                reference = reference.Substring(prefix.Length, reference.Length - prefix.Length - suffix.Length);
                             }
                         }
                     }