Fix a few notices

lib/forez/tour/join_group_pane.dart

@@ -36,8 +36,7 @@ class _JoinGroupPaneBody extends StatefulWidget {
   const _JoinGroupPaneBody({
     Key? key,
     required this.onUpdated,
-  })  : assert(onUpdated != null),
-        super(key: key);
+  })  : super(key: key);
 
   @override
   JoinGroupPaneBodyState createState() => JoinGroupPaneBodyState();

lib/forez/ui/routes/forez_member_profile_route.dart

@@ -26,8 +26,7 @@ class ForezMemberProfileRoute extends StatefulWidget {
   const ForezMemberProfileRoute({
     Key? key,
     required this.userID,
-  })  : assert(userID != null),
-        super(key: key);
+  }) : super(key: key);
 
   @override
   _ForezMemberProfileRouteState createState() =>

lib/forez/ui/routes/forez_route.dart

@@ -210,7 +210,5 @@ class _Tab {
     required this.title,
     required this.widget,
     this.isUnread,
-  })  : assert(icon != null),
-        assert(title != null),
-        assert(widget != null);
+  });
 }

lib/forez/ui/routes/search_users.dart

@@ -15,7 +15,7 @@ Future<User?> searchUser(BuildContext context, UsersList users) async {
 class _SearchDelegate extends SearchDelegate<User?> {
   final UsersList _usersList;
 
-  _SearchDelegate(this._usersList) : assert(_usersList != null);
+  _SearchDelegate(this._usersList);
 
   @override
   List<Widget>? buildActions(BuildContext context) => null;

lib/forez/ui/screens/forez_directory_screen.dart

@@ -207,12 +207,7 @@ class _MembershipButton extends StatelessWidget {
     required this.onTap,
     required this.color,
     required this.icon,
-  })  : assert(user != null),
-        assert(action != null),
-        assert(onTap != null),
-        assert(color != null),
-        assert(icon != null),
-        super(key: key);
+  }) : super(key: key);
 
   @override
   Widget build(BuildContext context) => ElevatedButton(