Crash if i login

[TillJohanndeiter]

I upgraded to powersync: ^1.16.0, and downloaded via dart run powersync:setup_web the new setup.

Then i get this error on web when i login. On the linux build everything works fine.

[PowerSync] FINE: 2025-10-03 16:31:16.678: [in] SyncWorkerMessageType.logEvent
[PowerSync] INFO: 2025-10-03 16:31:16.678: [Sync Worker]: [PowerSync] FINE: 2025-10-03 16:31:16.677: Broadcasting sync event: SyncStatus<connected: true connecting: false downloading: true (progress: for total: 4992 / 4992) uploading: false lastSyncedAt: null, hasSynced: null, error: null>
[PowerSync] FINE: 2025-10-03 16:31:16.679: [in] SyncWorkerMessageType.notifySyncStatus
DartError: TypeError: null: type 'Null' is not a subtype of type 'List<dynamic>'
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 274:3       throw_
dart-sdk/lib/_internal/js_shared/lib/rti.dart 1503:3                              _generalAsCheckImplementation
package:powersync_core/src/web/sync_worker_protocol.dart 334:14                   <fn>
package:powersync_core/src/web/sync_worker_protocol.dart 331:26                   SerializedSyncStatus.asSyncStatus
package:powersync_core/src/web/sync_controller.dart 76:55                         <fn>
dart-sdk/lib/async/zone.dart 1778:9                                               runUnaryGuarded
dart-sdk/lib/async/stream_impl.dart 381:5                                         [_sendData]
dart-sdk/lib/async/stream_impl.dart 573:13                                        perform
dart-sdk/lib/async/stream_impl.dart 678:10                                        handleNext
dart-sdk/lib/async/stream_impl.dart 649:7                                         <fn>
dart-sdk/lib/async/schedule_microtask.dart 40:34                                  _microtaskLoop
dart-sdk/lib/async/schedule_microtask.dart 49:5                                   _startMicrotaskLoop
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 118:77  tear
dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 188:69               <fn>
[PowerSync] FINE: 2025-10-03 16:31:16.957: [in] SyncWorkerMessageType.logEvent
[PowerSync] INFO: 2025-10-03 16:31:16.958: [Sync Worker]: [PowerSync] FINE: 2025-10-03 16:31:16.957: validated checkpoint: Instance of 'minified:cX'
[PowerSync] FINE: 2025-10-03 16:31:16.959: [in] SyncWorkerMessageType.logEvent
[PowerSync] INFO: 2025-10-03 16:31:16.959: [Sync Worker]: [PowerSync] FINE: 2025-10-03 16:31:16.958: Broadcasting sync event: SyncStatus<connected: true connecting: false downloading: false (progress: null) uploading: false lastSyncedAt: 2025-10-03 16:31:16.957, hasSynced: null, error: null>
[PowerSync] FINE: 2025-10-03 16:31:16.959: [in] SyncWorkerMessageType.notifySyncStatus
DartError: TypeError: null: type 'Null' is not a subtype of type 'List<dynamic>'
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 274:3       throw_
dart-sdk/lib/_internal/js_shared/lib/rti.dart 1503:3                              _generalAsCheckImplementation
package:powersync_core/src/web/sync_worker_protocol.dart 334:14                   <fn>
package:powersync_core/src/web/sync_worker_protocol.dart 331:26                   SerializedSyncStatus.asSyncStatus
package:powersync_core/src/web/sync_controller.dart 76:55                         <fn>
dart-sdk/lib/async/zone.dart 1778:9                                               runUnaryGuarded
dart-sdk/lib/async/stream_impl.dart 381:5                                         [_sendData]
dart-sdk/lib/async/stream_impl.dart 573:13                                        perform
dart-sdk/lib/async/stream_impl.dart 678:10                                        handleNext
dart-sdk/lib/async/stream_impl.dart 649:7                                         <fn>
dart-sdk/lib/async/schedule_microtask.dart 40:34                                  _microtaskLoop
dart-sdk/lib/async/schedule_microtask.dart 49:5                                   _startMicrotaskLoop
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 118:77  tear
dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 188:69       

Here is my powersync service

Future<void> openPowerSyncDatabase() async {
  db = PowerSyncDatabase(schema: schema, path: await getDatabasePath());
  await db.initialize();
  PowerSyncSupabaseConnector? currentConnector;

  if (isLoggedIn()) {
    currentConnector = PowerSyncSupabaseConnector();
    await db.connect(connector: currentConnector);
  }

  Supabase.instance.client.auth.onAuthStateChange.listen((data) async {
    final AuthChangeEvent event = data.event;
    if (event == AuthChangeEvent.signedIn) {
      currentConnector = PowerSyncSupabaseConnector();
      await db.connect(connector: currentConnector!);
    } else if (event == AuthChangeEvent.signedOut) {
      currentConnector = null;
      await db.disconnect();
    } else if (event == AuthChangeEvent.tokenRefreshed) {
      await currentConnector?.prefetchCredentials();
    }
  });
}


class PowerSyncSupabaseConnector extends PowerSyncBackendConnector {
  Future<void>? _refreshFuture;

  PowerSyncSupabaseConnector();

  @override
  Future<PowerSyncCredentials?> fetchCredentials() async {
    await _refreshFuture;

    final session = Supabase.instance.client.auth.currentSession;
    if (session == null) {
      return null;
    }

    final token = session.accessToken;
....

    return PowerSyncCredentials(
        endpoint: powerSyncUrl,
        token: token,
        userId: userId,
        expiresAt: expiresAt);
  }

  @override
  void invalidateCredentials() {
    _refreshFuture = Supabase.instance.client.auth
        .refreshSession()
        .timeout(const Duration(seconds: 5))
        .then((response) => null, onError: (error) => null);
  }

  // Upload pending changes to Supabase.
  @override
  Future<void> uploadData(PowerSyncDatabase database) async {

I already tried to clear the cache. If i downgrade everything works fine.