fix customize_channel_preview example

example/ios/Flutter/.last_build_id

@@ -1 +1 @@
-c770358a10272b4ee1cdc2eb432445f6
+c1153e968f5d6bcc19c41ac2592825f6

example/lib/customize_channel_preview.dart

@@ -62,7 +62,7 @@ class ChannelListPage extends StatelessWidget {
             }
           },
           channelPreviewBuilder: _channelPreviewBuilder,
-          sort: [SortOption('last_message_at')],
+          // sort: [SortOption('last_message_at')],
           pagination: PaginationParams(
             limit: 20,
           ),
@@ -73,8 +73,10 @@ class ChannelListPage extends StatelessWidget {
   }
 
   Widget _channelPreviewBuilder(BuildContext context, Channel channel) {
-    final lastMessage = channel.state.messages.reversed
-        .firstWhere((message) => !message.isDeleted);
+    final lastMessage = channel.state.messages.reversed.firstWhere(
+      (message) => !message.isDeleted,
+      orElse: () => null,
+    );
 
     final subtitle = (lastMessage == null ? "nothing yet" : lastMessage.text);
     final opacity = channel.state.unreadCount > .0 ? 1.0 : 0.5;