migrate error builder callback using typedef

packages/flutter_widgets/lib/src/channel_list_view.dart

@@ -167,7 +167,7 @@ class _ChannelListViewState extends State<ChannelListView>
       emptyBuilder: (BuildContext context) {
         return _buildEmptyWidget();
       },
-      errorBuilder: (Error error) {
+      errorBuilder: (BuildContext context, dynamic error) {
         return _buildErrorWidget(context);
       },
       loadingBuilder: (BuildContext context) {

packages/flutter_widgets/lib/src/message_search_list_view.dart

@@ -148,7 +148,7 @@ class _MessageSearchListViewState extends State<MessageSearchListView> {
           },
         );
       },
-      errorBuilder: (error) {
+      errorBuilder: (BuildContext context, dynamic error) {
         if (error is Error) {
           print((error).stackTrace);
         }