better handle when room is null

lib/controllers/room_chat_controller.dart

@@ -14,18 +14,20 @@ import "package:nexus/models/relation_type.dart";
 import "package:nexus/models/requests/send_message_request.dart";
 import "package:nexus/models/room.dart";
 
-class RoomChatController extends AsyncNotifier<IList<Event>> {
+class RoomChatController extends AsyncNotifier<IList<Event>?> {
   final String roomId;
   RoomChatController(this.roomId);
 
   @override
-  Future<IList<Event>> build() async {
+  Future<IList<Event>?> build() async {
     final client = ref.watch(ClientController.provider.notifier);
     final room = ref.watch(
       RoomsController.provider.select((rooms) => rooms[roomId]),
     );
 
-    if (!room!.hasFetchedState) {
+    if (room == null) return null;
+
+    if (!room.hasFetchedState) {
       final state = await client.getRoomState(.new(roomId: roomId));
 
       await ref.read(RoomsController.provider.notifier).addState(roomId, state);
@@ -214,7 +216,7 @@ class RoomChatController extends AsyncNotifier<IList<Event>> {
   }
 
   static final provider = AsyncNotifierProvider.family
-      .autoDispose<RoomChatController, IList<Event>, String>(
+      .autoDispose<RoomChatController, IList<Event>?, String>(
         RoomChatController.new,
       );
 }

lib/widgets/room_appbar.dart

@@ -1,4 +1,3 @@
-import "package:fast_immutable_collections/fast_immutable_collections.dart";
 import "package:flutter/material.dart";
 import "package:hooks_riverpod/hooks_riverpod.dart";
 import "package:nexus/controllers/rooms_controller.dart";
@@ -93,13 +92,15 @@ class RoomAppbar extends ConsumerWidget implements PreferredSizeWidget {
                 ),
               ),
             ),
-      leading: isDesktop && room != null
-          ? AvatarOrHash(
-              room.metadata?.avatar,
-              room.metadata?.name ?? "Unnamed Room",
-              height: 24,
-              fallback: Icon(Icons.numbers),
-            )
+      leading: isDesktop
+          ? room == null
+                ? null
+                : AvatarOrHash(
+                    room.metadata?.avatar,
+                    room.metadata?.name ?? "Unnamed Room",
+                    height: 24,
+                    fallback: Icon(Icons.numbers),
+                  )
           : DrawerButton(onPressed: () => onOpenDrawer(context)),
       scrolledUnderElevation: 0,
       title: room == null
@@ -123,19 +124,21 @@ class RoomAppbar extends ConsumerWidget implements PreferredSizeWidget {
                   ),
               ],
             ),
-      actions: [
-        IconButton(
-          onPressed: null,
-          icon: Icon(Icons.push_pin),
-          tooltip: "Open pinned messages",
-        ),
-        IconButton(
-          onPressed: () => onOpenMemberList?.call(context),
-          tooltip: "Open member list",
-          icon: Icon(Icons.people),
-        ),
-        if (room != null) RoomMenu(room),
-      ].toIList(),
+      actions: room == null
+          ? .new()
+          : .new([
+              IconButton(
+                onPressed: null,
+                icon: Icon(Icons.push_pin),
+                tooltip: "Open pinned messages",
+              ),
+              IconButton(
+                onPressed: () => onOpenMemberList?.call(context),
+                tooltip: "Open member list",
+                icon: Icon(Icons.people),
+              ),
+              RoomMenu(room),
+            ]),
     );
   }
 }

lib/widgets/room_chat.dart

@@ -50,6 +50,12 @@ class RoomChat extends HookConsumerWidget {
     final userId = ref.watch(ClientStateController.provider)?.userId;
     final theme = Theme.of(context);
 
+    final nothing = Center(
+      child: Text(
+        "Nothing to see here...",
+        style: theme.textTheme.headlineMedium,
+      ),
+    );
     if (userId == null || this.roomId == null) {
       return Scaffold(
         appBar: RoomAppbar(
@@ -58,12 +64,7 @@ class RoomChat extends HookConsumerWidget {
           onOpenDrawer: (_) => Scaffold.of(context).openDrawer(),
           onOpenMemberList: null,
         ),
-        body: Center(
-          child: Text(
-            "Nothing to see here...",
-            style: theme.textTheme.headlineMedium,
-          ),
-        ),
+        body: nothing,
       );
     }
 
@@ -81,7 +82,7 @@ class RoomChat extends HookConsumerWidget {
     final topEventBeforeLoad = useState<String?>(null);
 
     Future<void> loadOlder() async {
-      if (controllerData case AsyncData(:final value)) {
+      if (controllerData case AsyncData(:final value?)) {
         topEventBeforeLoad.value = value.firstOrNull?.eventId;
         await notifier.loadOlder();
       }
@@ -105,7 +106,7 @@ class RoomChat extends HookConsumerWidget {
 
     useEffect(() {
       if (controllerData case AsyncData(
-        :final value,
+        :final value?,
       ) when scrollController.hasClients) {
         if (topEventBeforeLoad.value != null) {
           WidgetsBinding.instance.addPostFrameCallback((_) {
@@ -401,7 +402,7 @@ class RoomChat extends HookConsumerWidget {
                   child: Padding(
                     padding: .symmetric(horizontal: 12),
                     child: switch (controllerData) {
-                      AsyncData(:final value) ||
+                      AsyncData(:final value?) ||
                       AsyncLoading(:final value?) => CustomScrollView(
                         controller: scrollController,
                         slivers: [
@@ -467,6 +468,7 @@ class RoomChat extends HookConsumerWidget {
                           ),
                         ],
                       ),
+                      AsyncData() => nothing,
                       AsyncLoading() => Loading(),
                       AsyncError(:final error, :final stackTrace) =>
                         ErrorDialog(error, stackTrace),

lib/widgets/sidebar.dart

@@ -39,9 +39,7 @@ class Sidebar extends HookConsumerWidget {
       (room) => room.metadata?.id == selectedRoomId,
     );
     final selectedRoomIndex = indexOfSelectedRoom == -1
-        ? selectedSpace.children.isEmpty
-              ? null
-              : 0
+        ? null
         : indexOfSelectedRoom;
 
     return Drawer(