chore: Follow up design changes

lib/pages/chat_members/chat_members.dart

@@ -52,6 +52,8 @@ class ChatMembersController extends State<ChatMembersPage> {
           .getRoomById(widget.roomId)
           ?.requestParticipants();
 
+      if (!mounted) return;
+
       setState(() {
         members = participants;
       });

lib/pages/chat_members/chat_members_view.dart

@@ -43,7 +43,7 @@ class ChatMembersView extends StatelessWidget {
         ),
         actions: [
           IconButton(
-            onPressed: () => context.go('/rooms/{room.id}/invite'),
+            onPressed: () => context.go('/rooms/${room.id}/invite'),
             icon: const Icon(
               Icons.person_add_outlined,
             ),

lib/pages/invitation_selection/invitation_selection_view.dart

@@ -15,7 +15,19 @@ class InvitationSelectionView extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final room = Matrix.of(context).client.getRoomById(controller.roomId!)!;
+    final room =
+        Matrix.of(context).client.getRoomById(controller.widget.roomId);
+    if (room == null) {
+      return Scaffold(
+        appBar: AppBar(
+          title: Text(L10n.of(context)!.oopsSomethingWentWrong),
+        ),
+        body: Center(
+          child: Text(L10n.of(context)!.youAreNoLongerParticipatingInThisChat),
+        ),
+      );
+    }
+
     final groupName = room.name.isEmpty ? L10n.of(context)!.group : room.name;
     return Scaffold(
       appBar: AppBar(