fix: show password required error instead of crashing when no stored password (#235)

During _load(), check whether a password exists in secure storage and track the result
in _hasStoredPassword. The password field validator now requires user input when no
password is stored, so _tryConnection() fails fast at form validation instead of
throwing an unhandled StateError.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/ui/screens/edit_account_screen.dart

@@ -38,6 +38,7 @@ class _EditAccountScreenState extends ConsumerState<EditAccountScreen> {
   var _sieveSsl = true;
   var _verbose = false;
   final _jmapUrlCtrl = TextEditingController();
+  bool _hasStoredPassword = false;
 
   // -- "Try connection" state ------------------------------------------------
   bool _tryTesting = false;
@@ -63,6 +64,11 @@ class _EditAccountScreenState extends ConsumerState<EditAccountScreen> {
       context.pop();
       return;
     }
+    try {
+      await repo.getPassword(account.id);
+      _hasStoredPassword = true;
+    } catch (_) {}
+    if (!mounted) return;
     _account = account;
     _displayNameCtrl.text = account.displayName;
     _usernameCtrl.text = account.username;
@@ -267,10 +273,12 @@ class _EditAccountScreenState extends ConsumerState<EditAccountScreen> {
             ),
             _field(
               _passwordCtrl,
-              'New password (leave blank to keep)',
+              _hasStoredPassword
+                  ? 'New password (leave blank to keep)'
+                  : 'Password',
               key: const Key('editPasswordField'),
               obscure: true,
-              required: false,
+              required: !_hasStoredPassword,
             ),
             if (account.type == AccountType.jmap) ...[
               const Divider(height: 32),

test/widget/edit_account_screen_test.dart

@@ -105,6 +105,32 @@ void main() {
       expect(find.text('Edit account'), findsNothing);
     });
 
+    testWidgets('try connection shows password required when no password stored', (
+      tester,
+    ) async {
+      tester.view.physicalSize = const Size(800, 1400);
+      tester.view.devicePixelRatio = 1.0;
+      addTearDown(tester.view.resetPhysicalSize);
+      addTearDown(tester.view.resetDevicePixelRatio);
+
+      await tester.pumpWidget(
+        buildApp(
+          initialLocation: '/accounts/acc-1/edit',
+          overrides: baseOverrides(
+            accounts: [kTestAccount],
+            hasStoredPassword: false,
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.byKey(const Key('editTryConnectionButton')));
+      await tester.pumpAndSettle();
+
+      // App must not crash; password field shows a validation error.
+      expect(find.text('Required'), findsOneWidget);
+    });
+
     testWidgets('connection error shows error message', (tester) async {
       tester.view.physicalSize = const Size(800, 1400);
       tester.view.devicePixelRatio = 1.0;

test/widget/helpers.dart

@@ -44,11 +44,12 @@ import 'package:sharedinbox/ui/screens/thread_detail_screen.dart';
 // ---------------------------------------------------------------------------
 
 class FakeAccountRepository implements AccountRepository {
-  final List<Account> _accounts;
-
   FakeAccountRepository([List<Account>? accounts])
       : _accounts = List.of(accounts ?? []);
 
+  final List<Account> _accounts;
+  bool hasPassword = true;
+
   @override
   Stream<List<Account>> observeAccounts() => Stream.value(List.of(_accounts));
 
@@ -75,7 +76,12 @@ class FakeAccountRepository implements AccountRepository {
       _accounts.removeWhere((a) => a.id == id);
 
   @override
-  Future<String> getPassword(String accountId) async => 'test-password';
+  Future<String> getPassword(String accountId) async {
+    if (!hasPassword) {
+      throw StateError('No password stored for account $accountId');
+    }
+    return 'test-password';
+  }
 }
 
 class FakeShareKeyRepository implements ShareKeyRepository {
@@ -511,10 +517,12 @@ List<Override> baseOverrides({
   List<Mailbox>? mailboxes,
   DiscoveryResult? discovery,
   Exception? connectionError,
+  bool hasStoredPassword = true,
 }) =>
     [
-      accountRepositoryProvider
-          .overrideWithValue(FakeAccountRepository(accounts)),
+      accountRepositoryProvider.overrideWithValue(
+        FakeAccountRepository(accounts)..hasPassword = hasStoredPassword,
+      ),
       mailboxRepositoryProvider
           .overrideWithValue(FakeMailboxRepository(mailboxes)),
       emailRepositoryProvider.overrideWithValue(FakeEmailRepository()),