Refactor notification handling in SidebarCommunitiesList for improved readability and maintainability.

lib/common/widgets/sidebar_communities_list.dart

@@ -16,6 +16,16 @@ class SidebarCommunitiesList extends StatelessWidget {
   final ScrollController scrollController;
   final void Function() onScrollToEnd;
 
+  bool _onNotification(ScrollEndNotification notification) {
+    final hasReachedEnd = notification.metrics.extentAfter == 0;
+    if (hasReachedEnd) {
+      onScrollToEnd.call();
+      return true;
+    }
+
+    return false;
+  }
+
   @override
   Widget build(BuildContext context) {
     return SingleChildScrollView(
@@ -26,17 +36,11 @@ class SidebarCommunitiesList extends StatelessWidget {
           scrollbarOrientation: ScrollbarOrientation.left,
           thumbVisibility: true,
           controller: scrollController,
-          child: NotificationListener(
+          child: NotificationListener<ScrollEndNotification>(
-            onNotification: (notification) {
+            onNotification: _onNotification,
-              if (notification is ScrollEndNotification &&
-                  notification.metrics.extentAfter == 0) {
-                onScrollToEnd.call();
-              }
-              return false;
-            },
             child: ListView.builder(
-              padding: const EdgeInsetsDirectional.only(start: 16),
               shrinkWrap: true,
+              padding: const EdgeInsetsDirectional.only(start: 16),
               itemCount: communities.length,
               controller: scrollController,
               itemBuilder: itemBuilder,