fix: честные ошибки при вводе пароля и дубликат в Keychain

lib/core/storage/token_storage.dart

@@ -1,3 +1,4 @@
+import 'package:flutter/services.dart' show PlatformException;
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
@@ -14,10 +15,25 @@ class TokenStorage {
     mOptions: MacOsOptions(usesDataProtectionKeychain: false),
   );
 
-  static Future<void> writeSecure(String key, String value) async {
-    await _secure.write(key: key, value: value);
+  static const int _duplicateKeychainItem = -25299;
+
+  static bool _isDuplicateItem(PlatformException error) =>
+      error.details == _duplicateKeychainItem ||
+      (error.message?.contains('$_duplicateKeychainItem') ?? false);
+
+  static Future<void> _write(String key, String value) async {
+    try {
+      await _secure.write(key: key, value: value);
+    } on PlatformException catch (e) {
+      if (!_isDuplicateItem(e)) rethrow;
+      await _secure.delete(key: key);
+      await _secure.write(key: key, value: value);
+    }
   }
 
+  static Future<void> writeSecure(String key, String value) =>
+      _write(key, value);
+
   static Future<String?> readSecure(String key) async {
     return _secure.read(key: key);
   }
@@ -31,9 +47,8 @@ class TokenStorage {
     return all.keys.where((key) => key.startsWith(prefix)).toList();
   }
 
-  static Future<void> saveToken(String token, int accountId) async {
-    await _secure.write(key: '$_tokenPrefix$accountId', value: token);
-  }
+  static Future<void> saveToken(String token, int accountId) =>
+      _write('$_tokenPrefix$accountId', token);
 
   static Future<String?> readToken(int accountId) async {
     final key = '$_tokenPrefix$accountId';
@@ -43,7 +58,7 @@ class TokenStorage {
     final prefs = await SharedPreferences.getInstance();
     final legacy = prefs.getString(key);
     if (legacy != null) {
-      await _secure.write(key: key, value: legacy);
+      await _write(key, legacy);
       await prefs.remove(key);
       return legacy;
     }