diff --git a/lib/utils/signal_wrapper.dart b/lib/utils/signal_wrapper.dart
index 8ccf706..eeda75e 100644
--- a/lib/utils/signal_wrapper.dart
+++ b/lib/utils/signal_wrapper.dart
@@ -46,7 +46,7 @@ class _MultiSignalWrapper implements SignalWrapper {
   });
 
   final Iterable<ProcessSignal> _signals;
-  final Completer<ProcessSignal> _completer;
+  final Completer<Null> _completer;
 
   @override
   final OnDisposeCallback? onDispose;
@@ -63,15 +63,13 @@ class _MultiSignalWrapper implements SignalWrapper {
     final subscriptions = [
       for (final signal in _signals)
         signal.watch().listen((signal) {
+          if (!_completer.isCompleted) _completer.complete(null);
           if (onSignal?.call(signal) case final Future f) futures.add(f);
-          if (!_completer.isCompleted) _completer.complete(signal);
         }),
     ];
 
     try {
-      final result = await Future.any([_completer.future, fn()]);
-      if (result is T) return result;
-      return null;
+      return await Future.any([_completer.future, fn()]);
     } catch (_) {
       rethrow;
     } finally {
@@ -106,8 +104,8 @@ class _SingleSignalWrapper implements SignalWrapper {
   Future<T?> call<T>(Future<T> Function() fn) async {
     final futures = <Future>[];
     final subscription = _signal.watch().listen((signal) {
-      if (onSignal?.call(signal) case final Future future) futures.add(future);
       if (!_completer.isCompleted) _completer.complete(null);
+      if (onSignal?.call(signal) case final Future future) futures.add(future);
     });
 
     try {
diff --git a/lib/utils/speed_monitor.dart b/lib/utils/speed_monitor.dart
index cd30125..5e253a5 100644
--- a/lib/utils/speed_monitor.dart
+++ b/lib/utils/speed_monitor.dart
@@ -10,20 +10,19 @@ final class _SpeedSample with LinkedListEntry<_SpeedSample> {
 }
 
 /// A utility class for monitoring processing speed over a sliding time window.
-///
-/// It tracks the number of units processed over a specified [windowDuration]
-/// (defaulting to 1 second) and calculates the current speed.
 class SpeedMonitor implements Disposable {
   static const double _zero = 0;
 
-  /// Creates a [SpeedMonitor] with a given [windowDuration].
+  /// Creates a [SpeedMonitor]
   factory SpeedMonitor() => ._(samples: .new());
 
-  const SpeedMonitor._({required this._samples})
-    : windowDuration = const .new(seconds: 1);
+  const SpeedMonitor._({
+    required this._samples,
+    this._windowDuration = const .new(seconds: 1),
+  });
 
   /// The duration of the sliding window used for speed calculation.
-  final Duration windowDuration;
+  final Duration _windowDuration;
 
   /// A linked list of samples currently within the time window.
   final LinkedList<_SpeedSample> _samples;
@@ -34,9 +33,6 @@ class SpeedMonitor implements Disposable {
   }
 
   /// Adds a sample of the [totalProcessedUnits] and returns the current speed.
-  ///
-  /// The speed is calculated as units per [windowDuration].
-  /// It automatically removes samples that are older than the [windowDuration].
   double add(int totalProcessedUnits) {
     final _SpeedSample last = .new(totalProcessedUnits);
 
@@ -48,13 +44,13 @@ class SpeedMonitor implements Disposable {
 
     int baseDeltaTime = last.time - first.time;
 
-    while (baseDeltaTime > windowDuration.inMicroseconds) {
+    while (baseDeltaTime > _windowDuration.inMicroseconds) {
       first.unlink();
       first = _samples.first;
       baseDeltaTime = last.time - first.time;
     }
 
-    final deltaTime = baseDeltaTime / windowDuration.inMicroseconds;
+    final deltaTime = baseDeltaTime / _windowDuration.inMicroseconds;
 
     final deltaUnits = last.units - first.units;
 
diff --git a/modules/local_store/lib/src/json_local_store.dart b/modules/local_store/lib/src/json_local_store.dart
index 0cdc017..3093fe4 100644
--- a/modules/local_store/lib/src/json_local_store.dart
+++ b/modules/local_store/lib/src/json_local_store.dart
@@ -1,21 +1,22 @@
 part of "local_store.dart";
 
 class _JSONLocalStore implements LocalStore {
-  static final _jsonBase64Decoder = utf8.decoder
+  static final Converter<List<int>, Object?> _jsonBase64Decoder = utf8.decoder
       .fuse(base64.decoder)
       .fuse(utf8.decoder)
       .fuse(json.decoder);
 
-  static final _jsonBase64Encoder = json.encoder
+  static final Converter<Object?, List<int>> _jsonBase64Encoder = json.encoder
       .fuse(utf8.encoder)
-      .fuse(base64.encoder);
+      .fuse(base64.encoder)
+      .fuse(utf8.encoder);
 
-  _JSONLocalStore(this.path);
+  _JSONLocalStore(this.path) : _cache = .new(), _file = .new(path);
 
   final String path;
-  late final File _file = .new(path);
 
-  final _cache = <String, dynamic>{};
+  final Map<String, dynamic> _cache;
+  final File _file;
 
   Completer<void>? _loadCompleter;
 
@@ -30,13 +31,12 @@ class _JSONLocalStore implements LocalStore {
     } catch (_) {
     } finally {
       completer.complete();
-      if (completer != _loadCompleter) _loadCompleter?.complete();
     }
   }
 
   Future<void> _save() async {
     if (!await _file.exists()) await _file.create(recursive: true);
-    await _file.writeAsString(_jsonBase64Encoder.convert(_cache), flush: true);
+    await _file.writeAsBytes(_jsonBase64Encoder.convert(_cache), flush: true);
   }
 
   @override
diff --git a/modules/nested_map/lib/src/extension.dart b/modules/nested_map/lib/src/extension.dart
index d13ca60..f3ff659 100644
--- a/modules/nested_map/lib/src/extension.dart
+++ b/modules/nested_map/lib/src/extension.dart
@@ -6,6 +6,7 @@ extension MapExtension<K extends String> on Map<K, dynamic> {
   dynamic _nestedGet(List<K> keys) {
     return switch (this[keys.removeAt(0)]) {
       final Map<K, dynamic> map => map._nestedGet(keys),
+      final List list => list._nestedGet(keys),
       final value => value,
     };
   }
@@ -32,3 +33,15 @@ extension MapExtension<K extends String> on Map<K, dynamic> {
     _nestedSet(keys, lastKey, value);
   }
 }
+
+extension ListExtension on List {
+  dynamic _nestedGet(List<String> keys) {
+    if (int.tryParse(keys.removeAt(0)) case final index?) {
+      return switch (this[index]) {
+        final List list => list._nestedGet(keys),
+        final Map<String, dynamic> map => map._nestedGet(keys),
+        final value => value,
+      };
+    }
+  }
+}