feat: fix hd wallet signatures

lib/src/4337/wallet.dart

@@ -139,10 +139,10 @@ class SmartWallet with _PluginManager implements SmartWalletBase {
   @override
   Future<SmartWallet> createSimpleAccount(Uint256 salt, {int? index}) async {
     EthereumAddress signer = EthereumAddress.fromHex(
-        plugin<MultiSignerInterface>('signer').getAddress());
+        plugin<MultiSignerInterface>('signer').getAddress(index: index ?? 0));
     _initCalldata = _getInitCallData('createAccount', [signer, salt.value]);
     await getSimpleAccountAddress(signer, salt)
-        .then((value) => {_walletAddress = value});
+        .then((addr) => {_walletAddress = addr});
     return this;
   }
 
@@ -170,25 +170,17 @@ class SmartWallet with _PluginManager implements SmartWalletBase {
   @override
   Future<EthereumAddress> getSimpleAccountAddress(
       EthereumAddress signer, Uint256 salt) {
-    try {
-      return plugin<_AccountFactory>('factory').getAddress(signer, salt.value);
-    } catch (e) {
-      throw SmartWalletError("Simple acount creation error: $e");
-    }
+    return plugin<_AccountFactory>('factory').getAddress(signer, salt.value);
   }
 
   @override
   Future<EthereumAddress> getSimplePassKeyAccountAddress(
       PassKeyPair pkp, Uint256 salt) {
-    try {
-      return plugin<_AccountFactory>('factory').getPasskeyAccountAddress(
-          pkp.credentialHexBytes,
-          pkp.publicKey[0].value,
-          pkp.publicKey[1].value,
-          salt.value);
-    } catch (e) {
-      throw SmartWalletError("Passkey acount creation error: $e");
-    }
+    return plugin<_AccountFactory>('factory').getPasskeyAccountAddress(
+        pkp.credentialHexBytes,
+        pkp.publicKey[0].value,
+        pkp.publicKey[1].value,
+        salt.value);
   }
 
   @override
@@ -244,9 +236,14 @@ class SmartWallet with _PluginManager implements SmartWalletBase {
     final opHash = userOp.hash(_chain);
 
     Uint8List signature = await plugin<MultiSignerInterface>('signer')
-        .personalSign(opHash,
+        .personalSign(
+            opHash,
             index: index,
-            id: id ?? plugin<PasskeyInterface>('signer').defaultId);
+            id: id ??
+                (plugin('signer') is PasskeyInterface
+                    ? plugin('signer').defaultId
+                    : id));
+
     userOp.signature = hexlify(signature);
 
     await _validateUserOperation(userOp);

lib/src/common/uint256.dart

@@ -65,7 +65,12 @@ class Uint256 implements Uint256Base {
   }
 
   @override
-  double toUnit(int decimals) {
+  BigInt toUnit(int decimals) {
+    return _value * BigInt.from(pow(10, decimals));
+  }
+
+  @override
+  double fromUnit(int decimals) {
     return _value / BigInt.from(pow(10, decimals));
   }
 

lib/src/interfaces/uint256_interface.dart

@@ -62,10 +62,29 @@ abstract class Uint256Base {
   @override
   String toString();
 
-  /// Converts this Uint256 to a [double] giving the [decimals].
+  /// The `toUnit` method is used to convert a Uint256 value from its base unit to a specific
+  /// unit. It takes an `int` parameter `decimals` which represents the number of decimal places
+  /// to consider. The method returns a `BigInt` representing the converted value.
+  /// example:
   ///
-  /// Returns an [double]
-  double toUnit(int decimals);
+  /// ```dart
+  /// Uint256(BigInt.from(1)).toUnit(18);
+  ///
+  /// // 1 * 10^18 = 1000000000000000000
+  /// ```
+  BigInt toUnit(int decimals);
+
+  /// The `fromUnit` method is used to convert a Uint256 value from a specific unit to its base
+  /// unit. It takes an `int` parameter `decimals` which represents the number of decimal places
+  /// to consider. The method returns a `double` representing the converted value.
+  /// example:
+  ///
+  /// ```dart
+  /// Uint256(BigInt.from(1000000000000000000)).fromUnit(18);
+  ///
+  /// // 1000000000000000000 / 10^18 = 1.0
+  /// ```
+  double fromUnit(int decimals);
 
   /// Converts this Uint256 to an [EtherAmount] in wei.
   ///

lib/src/signers/hd_wallet_signer.dart

@@ -1,21 +1,23 @@
 part of 'package:variance_dart/variance.dart';
 
 class HDWalletSigner with SecureStorageMixin implements HDInterface {
-  String? _mnemonic;
+  final String _mnemonic;
+
   final String _seed;
 
   late final EthereumAddress zerothAddress;
 
-  HDWalletSigner({required String seed}) : _seed = seed {
+  HDWalletSigner._internal({required String seed, required String mnemonic})
+      : _seed = seed,
+        _mnemonic = mnemonic {
     assert(seed.isNotEmpty, "seed cannot be empty");
   }
 
   /// Generates a new account in the HD wallet and stores it as zeroth.
   ///
   /// Returns the HD signer instance.
   factory HDWalletSigner.createWallet() {
-    final mnemonic = bip39.generateMnemonic();
-    return HDWalletSigner.recoverAccount(mnemonic);
+    return HDWalletSigner.recoverAccount(bip39.generateMnemonic());
   }
 
   /// Recovers an account from a mnemonic phrase and stores it in the HD wallet as zeroth.
@@ -25,7 +27,7 @@ class HDWalletSigner with SecureStorageMixin implements HDInterface {
   /// Returns the HD signer instance.
   factory HDWalletSigner.recoverAccount(String mnemonic) {
     final seed = bip39.mnemonicToSeedHex(mnemonic);
-    final signer = HDWalletSigner(seed: seed);
+    final signer = HDWalletSigner._internal(seed: seed, mnemonic: mnemonic);
     signer.zerothAddress = signer._add(seed, 0);
     return signer;
   }
@@ -52,7 +54,7 @@ class HDWalletSigner with SecureStorageMixin implements HDInterface {
   }
 
   @override
-  String? exportMnemonic() {
+  String exportMnemonic() {
     return _getMnemonic();
   }
 
@@ -115,8 +117,7 @@ class HDWalletSigner with SecureStorageMixin implements HDInterface {
     return _deriveHdKey(_seed, index);
   }
 
-  String? _getMnemonic() {
-    require(_mnemonic != null, "exportMnemonic: Not a Valid Wallet");
+  String _getMnemonic() {
     return _mnemonic;
   }