Fix for second tax rate

lib/data/models/invoice_model.dart

@@ -440,10 +440,19 @@ abstract class InvoiceEntity extends Object
     return actions..addAll(getBaseActions(user: user));
   }
 
-  InvoiceEntity applyTax(TaxRateEntity taxRate) {
-    InvoiceEntity invoice = rebuild((b) => b
-      ..taxRate1 = taxRate.rate
-      ..taxName1 = taxRate.name);
+  InvoiceEntity applyTax(TaxRateEntity taxRate, {bool isSecond = false}) {
+
+    InvoiceEntity invoice;
+
+    if (isSecond) {
+      invoice = rebuild((b) => b
+        ..taxRate2 = taxRate.rate
+        ..taxName2 = taxRate.name);
+    } else {
+      invoice = rebuild((b) => b
+        ..taxRate1 = taxRate.rate
+        ..taxName1 = taxRate.name);
+    }
 
     if (taxRate.isInclusive) {
       invoice = invoice.rebuild((b) => b

lib/main.dart

@@ -1,5 +1,4 @@
 import 'dart:async';
-
 import 'package:font_awesome_flutter/font_awesome_flutter.dart';
 import 'package:intl/intl.dart';
 import 'package:invoiceninja_flutter/.env.dart';

lib/ui/invoice/edit/invoice_edit_details.dart

@@ -300,8 +300,8 @@ class InvoiceEditDetailsState extends State<InvoiceEditDetails> {
             company.enableInvoiceTaxes && company.enableSecondTaxRate
                 ? TaxRateDropdown(
                     taxRates: company.taxRates,
-                    onSelected: (taxRate) =>
-                        viewModel.onChanged(invoice.applyTax(taxRate)),
+                    onSelected: (taxRate) => viewModel
+                        .onChanged(invoice.applyTax(taxRate, isSecond: true)),
                     labelText: localization.tax,
                     initialTaxName: invoice.taxName2,
                     initialTaxRate: invoice.taxRate2,