update throttling dependency

lib/implementations/debounce_lang_tool_service.dart

@@ -9,7 +9,7 @@ class DebounceLangToolService extends LanguageCheckService {
   final LanguageCheckService baseService;
 
   /// A debouncing used to debounce the API calls.
-  final Debouncing debouncing;
+  final Debouncing<Future<Result<List<Mistake>>?>> debouncing;
 
   /// Creates a new instance of the [DebounceLangToolService] class.
   DebounceLangToolService(
@@ -20,15 +20,15 @@ class DebounceLangToolService extends LanguageCheckService {
   @override
   Future<Result<List<Mistake>>> findMistakes(String text) async {
     final value =
-        await debouncing.debounce(() => baseService.findMistakes(text))
+        (await debouncing.debounce(() => baseService.findMistakes(text)) ?? [])
             as Result<List<Mistake>>;
 
     return value;
   }
 
   @override
   Future<void> dispose() async {
-    await debouncing.close();
+    debouncing.close();
     await baseService.dispose();
   }
 }

lib/implementations/throttling_lang_tool_service.dart

@@ -30,7 +30,7 @@ class ThrottlingLangToolService extends LanguageCheckService {
 
   @override
   Future<void> dispose() async {
-    await throttling.close();
+    throttling.close();
     await baseService.dispose();
   }
 }

pubspec.yaml

@@ -14,7 +14,7 @@ dependencies:
   flutter:
     sdk: flutter
   http: ^1.0.0
-  throttling: ^1.0.0
+  throttling: ^2.0.1
 
 dev_dependencies:
   flutter_test: