feat: add placeholder for empty list

lib/providers/settings.dart

@@ -189,7 +189,7 @@ class _SettingsProviderState extends State<SettingsProvider> {
         // activeLogin = null;
         // ready = true;
       });
-    });
+    }, 100);
   }
 
   // http timeout

lib/scaffolds/list.dart

@@ -4,6 +4,7 @@ import 'package:flutter/widgets.dart';
 import '../providers/settings.dart';
 import '../widgets/error_reload.dart';
 import '../widgets/loading.dart';
+import '../widgets/empty.dart';
 
 class ListPayload<T, K> {
   K cursor;
@@ -132,6 +133,8 @@ class _ListScaffoldState<T, K> extends State<ListScaffold<T, K>> {
       );
     } else if (loading) {
       return SliverToBoxAdapter(child: Loading(more: false));
+    } else if (items.isEmpty) {
+      return SliverToBoxAdapter(child: EmptyWidget());
     } else {
       return SliverList(
         delegate: SliverChildBuilderDelegate(
@@ -147,6 +150,8 @@ class _ListScaffoldState<T, K> extends State<ListScaffold<T, K>> {
       return ErrorReload(text: error, reload: _refresh);
     } else if (loading) {
       return Loading(more: false);
+    } else if (items.isEmpty) {
+      return EmptyWidget();
     } else {
       return ListView.builder(
         controller: _controller,

lib/screens/notifications.dart

@@ -6,6 +6,7 @@ import '../providers/settings.dart';
 import '../widgets/notification_item.dart';
 import '../widgets/list_group.dart';
 import '../widgets/link.dart';
+import '../widgets/empty.dart';
 import '../utils/utils.dart';
 
 String getRepoKey(NotificationGroup group) {
@@ -249,10 +250,12 @@ $key: pullRequest(number: ${item.number}) {
       loading: loading,
       error: error,
       bodyBuilder: () {
-        return Column(
-            children: groupMap.entries
-                .map((entry) => _buildGroupItem(context, entry))
-                .toList());
+        return groupMap.isEmpty
+            ? EmptyWidget()
+            : Column(
+                children: groupMap.entries
+                    .map((entry) => _buildGroupItem(context, entry))
+                    .toList());
       },
     );
   }

lib/utils/github.dart

@@ -1 +0,0 @@
-export 'package:github/server.dart';

lib/utils/utils.dart

@@ -3,7 +3,7 @@ import 'package:flutter/cupertino.dart';
 import 'package:flutter/gestures.dart';
 import '../providers/settings.dart';
 import '../screens/repo.dart';
-export 'github.dart';
+export 'package:github/server.dart';
 export 'octicons.dart';
 export 'timeago.dart';
 
@@ -14,9 +14,9 @@ Color convertColor(String cssHex) {
   return Color(int.parse('ff' + cssHex, radix: 16));
 }
 
-void nextTick(Function callback) {
+void nextTick(Function callback, [int milliseconds = 0]) {
   // FIXME:
-  Future.delayed(Duration(milliseconds: 100)).then((_) {
+  Future.delayed(Duration(milliseconds: 0)).then((_) {
     callback();
   });
 }

lib/widgets/empty.dart

@@ -0,0 +1,11 @@
+import 'package:flutter/material.dart';
+
+class EmptyWidget extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      padding: EdgeInsets.symmetric(vertical: 50),
+      child: Center(child: Text('Empty', style: TextStyle(fontSize: 18))),
+    );
+  }
+}

lib/widgets/list_group.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import '../widgets/empty.dart';
 
 class ListGroup<T> extends StatelessWidget {
   final Widget title;
@@ -30,7 +31,10 @@ class ListGroup<T> extends StatelessWidget {
               color: Color(0x10000000),
               child: title,
             ),
-            Column(children: items.asMap().entries.map(_buildItem).toList())
+            items.isEmpty
+                ? EmptyWidget()
+                : Column(
+                    children: items.asMap().entries.map(_buildItem).toList())
           ],
         ),
       ),