fix: scheme storage on web.

app/lib/models/local_schemes_web.dart

@@ -2,7 +2,6 @@ import 'dart:convert';
 import 'dart:html';
 
 import 'package:dde_gesture_manager/builder/provider_annotation.dart';
-import 'package:dde_gesture_manager/extensions.dart';
 import 'package:dde_gesture_manager/models/local_schemes_provider.dart';
 import 'package:dde_gesture_manager/models/scheme.dart';
 import 'package:uuid/uuid.dart';
@@ -19,28 +18,20 @@ class LocalSchemes implements LocalSchemesInterface<LocalSchemeEntryWeb> {
 
   @override
   Future<List<LocalSchemeEntryWeb>> get schemeEntries async {
-    return window.localStorage.keys
-        .map<LocalSchemeEntryWeb?>((key) {
-          if (key.startsWith('schemes.')) {
-            LocalSchemeEntryWeb? entry;
-            try {
-              var content = window.localStorage[key] ?? '';
-              var schemeJson = json.decode(content);
-              entry = LocalSchemeEntryWeb(
-                path: key,
-                scheme: Scheme.parse(schemeJson),
-                lastModifyTime: DateTime.parse(schemeJson['modified_at']),
-              );
-            } catch (e) {
-              e.sout();
-            }
-            return entry;
-          }
-          return null;
-        })
-        .where((e) => e != null)
-        .cast<LocalSchemeEntryWeb>()
-        .toList();
+    List<LocalSchemeEntryWeb> _localeSchemes = [];
+    for (var key in window.localStorage.keys) {
+      if (key.startsWith('schemes.')) {
+        var content = window.localStorage[key] ?? '';
+        var schemeJson = json.decode(content);
+        _localeSchemes.add(LocalSchemeEntryWeb(
+          path: key,
+          scheme: Scheme.parse(schemeJson),
+          lastModifyTime: DateTime.parse(schemeJson['modified_at']),
+        ));
+      }
+    }
+    print(_localeSchemes.join('\n'));
+    return Future.value(_localeSchemes);
   }
 
   @ProviderModelProp()
@@ -85,8 +76,8 @@ class LocalSchemeEntryWeb implements LocalSchemeEntry {
   @override
   save(LocalSchemesProvider provider) {
     var schemeMap = scheme.toJson();
-    schemeMap['modified_at'] = DateTime.now();
-    window.localStorage[path] = JsonEncoder.withIndent(' ' * 4).convert();
+    schemeMap['modified_at'] = DateTime.now().toIso8601String();
+    window.localStorage[path] = JsonEncoder.withIndent(' ' * 4).convert(schemeMap);
     provider.schemes!.firstWhere((ele) => ele.scheme.id == scheme.id).lastModifyTime = DateTime.now();
     provider.setProps(schemes: [...provider.schemes!]..sort());
   }