Fix all warnings

lib/ui/screens/notifications_screen.dart

@@ -316,6 +316,9 @@ class _NotificationTile extends StatelessWidget {
       case _PopupMenuActions.DELETE:
         onDelete(notification);
         break;
+
+      default:
+        break;
     }
   }
 

lib/ui/screens/other_friends_lists_screen.dart

@@ -88,7 +88,7 @@ class _OtherUserFriendsListScreenState
           user: _usersInfo!.getUser(_friendsList.elementAt(i)),
           onTap: (u) => openUserPage(
             context: context,
-            userID: u.id!,
+            userID: u.id,
           ),
         ),
       ),

lib/ui/screens/search_screen.dart

@@ -97,7 +97,7 @@ class _SearchResultUser extends StatelessWidget {
         user: user,
       ),
       title: Text(user.displayName),
-      onTap: () => MainController.of(context)!.openUserPage(user.id!),
+      onTap: () => MainController.of(context)!.openUserPage(user.id),
     );
   }
 }

lib/ui/screens/unread_conversations_screen.dart

@@ -102,7 +102,7 @@ class _UnreadConversationsScreenState
             ? _groups!.getGroup(conv.conv.groupID)
             : null,
       ),
-      title: Text(ConversationsHelper.getConversationName(conv.conv, _users)!),
+      title: Text(ConversationsHelper.getConversationName(conv.conv, _users)),
       subtitle: RichText(
         text: TextSpan(style: Theme.of(context).textTheme.bodyText2, children: [
           TextSpan(

lib/ui/screens/update_conversation_screen.dart

@@ -282,7 +282,7 @@ class _UpdateConversationScreen extends State<UpdateConversationScreen> {
   void _toggleAdminStatus(User user) async {
     try {
       final setAdmin = !_admins.contains(user.id);
-      await ConversationsHelper.setAdmin(_conversation.id!, user.id!, setAdmin);
+      await ConversationsHelper.setAdmin(_conversation.id!, user.id, setAdmin);
 
       setState(() {
         if (!setAdmin)