fix: fix errors in core-dart file

packages/core-dart/.dart_tool/package_config.json

@@ -298,7 +298,7 @@
   ],
   "generator": "pub",
   "generatorVersion": "3.9.2",
-  "flutterRoot": "file:///C:/Users/TCE%20HUB/fvm/versions/3.35.7",
+  "flutterRoot": "file:///C:/Users/TCE%20HUB/fvm/default",
   "flutterVersion": "3.35.7",
   "pubCache": "file:///C:/Users/TCE%20HUB/AppData/Local/Pub/Cache"
 }

packages/core-dart/lib/src/address/stellar_address.dart

@@ -1,8 +1,8 @@
 import 'package:meta/meta.dart';
-import '../address/codes.dart';
 import '../muxed/decode.dart';
-import '../address/detect.dart';
 import '../exceptions.dart';
+import 'codes.dart';
+import 'detect.dart';
 
 /// An immutable representation of a Stellar Address.
 @immutable
@@ -65,8 +65,8 @@ class StellarAddress {
       return StellarAddress._(
         kind: AddressKind.m,
         raw: address,
-        baseG: decoded['baseG'] as String?,
-        muxedId: decoded['id'] as BigInt?,
+        baseG: decoded.baseG,
+        muxedId: decoded.id,
       );
     } catch (error) {
       throw StellarAddressException(

packages/core-dart/lib/src/muxed/decode.dart

@@ -1,10 +1,20 @@
 import 'dart:typed_data';
 import '../util/strkey.dart';
 import 'decoded_muxed_address.dart';
+import '../exceptions.dart';
 
 class MuxedDecoder {
   static DecodedMuxedAddress decodeMuxedString(String mAddress) {
     final decoded = StrKeyUtil.decodeBase32(mAddress);
+
+    if (decoded.length != 43) {
+      throw const StellarAddressException('Invalid muxed address length');
+    }
+
+    if (decoded[0] != 0x60) {
+      throw const StellarAddressException('Invalid muxed address prefix');
+    }
+
     // Payload starts at index 1 (skip version byte 0x60)
     // 32 bytes pubkey + 8 bytes ID = 40 bytes
     final pubkey = decoded.sublist(1, 33);

packages/core-dart/lib/src/routing/extract.dart

@@ -51,8 +51,8 @@ RoutingResult extractRouting(RoutingInput input) {
   if (parsed.kind == AddressKind.m) {
     final warnings = List<Warning>.from(parsed.warnings);
     final decoded = MuxedDecoder.decodeMuxedString(parsed.address);
-    final baseG = decoded['baseG'] as String;
-    final muxedId = (decoded['id'] as BigInt).toString();
+    final baseG = decoded.baseG;
+    final muxedId = decoded.id.toString();
 
     if (input.memoType == 'none') {
       return RoutingResult(

packages/core-dart/test/debug_decode.dart

@@ -0,0 +1,12 @@
+import 'package:stellar_address_kit/stellar_address_kit.dart';
+
+void main() {
+  const baseG = 'GAYCUYT553C5LHVE2XPW5GMEJT4BXGM7AHMJWLAPZP53KJO7EIQADRSI';
+  try {
+    print('Testing decode on G address...');
+    final result = MuxedAddress.decode(baseG);
+    print('Result: $result');
+  } catch (e) {
+    print('Caught expected error: $e');
+  }
+}

packages/core-dart/test/muxed_round_trip_test.dart

@@ -11,7 +11,7 @@ BigInt _randomUint64(Random rng) {
   // Build 64 random bits from two 32-bit values.
   final hi = BigInt.from(rng.nextInt(1 << 32));
   final lo = BigInt.from(rng.nextInt(1 << 32));
-  return (hi << 32) | lo;
+  return (hi << 32) + lo;
 }
 
 void main() {
@@ -20,7 +20,7 @@ void main() {
   // Feature: muxed-decode-typed-dto, Property 1: Construction preserves field values
   // For any baseG string and BigInt id, DecodedMuxedAddress(baseG, id).baseG == baseG and .id == id
   group('Property 1: Construction preserves field values', () {
-    test('field values are preserved across $\_iterations random instances', () {
+    test('field values are preserved across $_iterations random instances', () {
       for (var i = 0; i < _iterations; i++) {
         final id = _randomUint64(rng);
         final dto = DecodedMuxedAddress(baseG: _baseG, id: id);
@@ -43,7 +43,7 @@ void main() {
   // Feature: muxed-decode-typed-dto, Property 2: Equality and hashCode consistency
   // For any two DecodedMuxedAddress instances, == and hashCode are consistent with field equality
   group('Property 2: Equality and hashCode consistency', () {
-    test('equal instances have equal hashCode across $\_iterations pairs', () {
+    test('equal instances have equal hashCode across $_iterations pairs', () {
       for (var i = 0; i < _iterations; i++) {
         final id = _randomUint64(rng);
         final a = DecodedMuxedAddress(baseG: _baseG, id: id);
@@ -68,7 +68,7 @@ void main() {
   // Feature: muxed-decode-typed-dto, Property 3: toString contains both fields
   // For any DecodedMuxedAddress, toString() contains baseG and id
   group('Property 3: toString contains both fields', () {
-    test('toString contains baseG and id across $\_iterations instances', () {
+    test('toString contains baseG and id across $_iterations instances', () {
       for (var i = 0; i < _iterations; i++) {
         final id = _randomUint64(rng);
         final dto = DecodedMuxedAddress(baseG: _baseG, id: id);
@@ -84,7 +84,7 @@ void main() {
   // Feature: muxed-decode-typed-dto, Property 4: Round-trip encode → decode → encode
   // For any valid baseG and uint64 id, encode then decode then re-encode is identity
   group('Property 4: Round-trip encode → decode → encode', () {
-    test('round-trip preserves baseG and id across $\_iterations random ids',
+    test('round-trip preserves baseG and id across $_iterations random ids',
         () {
       for (var i = 0; i < _iterations; i++) {
         final id = _randomUint64(rng);