fixed possible lockups on app start

lib/storage/hydrated_storage_bootstrap.dart

@@ -0,0 +1,54 @@
+import 'dart:developer';
+import 'dart:io';
+
+import 'package:hydrated_bloc/hydrated_bloc.dart';
+
+/// Opens the HydratedBloc box; a corrupt box is dropped and rebuilt, and if
+/// even that fails the app runs on [InMemoryStorage] instead of never
+/// reaching `runApp`.
+Future<Storage> buildHydratedStorageWithFallback(String directoryPath) async {
+  final directory = HydratedStorageDirectory(directoryPath);
+  try {
+    return await HydratedStorage.build(storageDirectory: directory);
+  } catch (e, s) {
+    log('HydratedStorage open failed, rebuilding: $e', stackTrace: s);
+  }
+  try {
+    await _deleteHydratedBox(directoryPath);
+    return await HydratedStorage.build(storageDirectory: directory);
+  } catch (e, s) {
+    log('HydratedStorage rebuild failed, using memory: $e', stackTrace: s);
+    return InMemoryStorage();
+  }
+}
+
+Future<void> _deleteHydratedBox(String directoryPath) async {
+  final directory = Directory(directoryPath);
+  if (!directory.existsSync()) return;
+  await for (final entity in directory.list()) {
+    final name = entity.uri.pathSegments.lastWhere((s) => s.isNotEmpty);
+    if (entity is File && name.startsWith('hydrated_box')) {
+      await entity.delete();
+    }
+  }
+}
+
+/// Non-persistent [Storage]; state lives for the session only.
+class InMemoryStorage implements Storage {
+  final Map<String, dynamic> _values = {};
+
+  @override
+  dynamic read(String key) => _values[key];
+
+  @override
+  Future<void> write(String key, dynamic value) async => _values[key] = value;
+
+  @override
+  Future<void> delete(String key) async => _values.remove(key);
+
+  @override
+  Future<void> clear() async => _values.clear();
+
+  @override
+  Future<void> close() async {}
+}