fix(ui): fix positioned list view null check

packages/stream_chat_flutter/lib/scrollable_positioned_list/src/positioned_list.dart

@@ -326,7 +326,7 @@ class _PositionedListState extends State<PositionedList> {
           final box = element.renderObject as RenderBox?;
           viewport ??= RenderAbstractViewport.of(box) as RenderViewport?;
           if (viewport == null || box == null) {
-            continue;
+            break;
           }
           final key = element.widget.key as IndexedKey;
           if (widget.scrollDirection == Axis.vertical) {

packages/stream_chat_flutter/lib/src/message_list_view.dart

@@ -399,8 +399,11 @@ class _MessageListViewState extends State<MessageListView> {
           final first = _itemPositionListener.itemPositions.value.first;
           final diff = newMessagesListLength - _messageListLength!;
           if (diff > 0) {
-            initialIndex = first.index + diff;
-            initialAlignment = first.itemLeadingEdge;
+            if (messages[0].user?.id !=
+                streamChannel!.channel.client.state.currentUser?.id) {
+              initialIndex = first.index + diff;
+              initialAlignment = first.itemLeadingEdge;
+            }
           }
         }
       }
@@ -1259,8 +1262,9 @@ class _MessageListViewState extends State<MessageListView> {
             event.message!.user!.id ==
                 streamChannel!.channel.client.state.currentUser!.id) {
           WidgetsBinding.instance!.addPostFrameCallback((_) {
-            _scrollController?.jumpTo(
+            _scrollController?.scrollTo(
               index: 0,
+              duration: const Duration(seconds: 1),
             );
           });
         }