Fix opening topic on non-existent message error display.

Telegram/SourceFiles/history/view/history_view_list_widget.cpp

@@ -535,6 +535,13 @@ void ListWidget::refreshRows(const Data::MessagesSlice &old) {
 
 std::optional<int> ListWidget::scrollTopForPosition(
 		Data::MessagePosition position) const {
+	auto messageUnknown = !position.date && position.fullId;
+	if (messageUnknown) {
+		if (const auto item = session().data().message(position.fullId)) {
+			position = item->position();
+			messageUnknown = false;
+		}
+	}
 	if (position == Data::UnreadMessagePosition) {
 		if (_bar.element && !_bar.hidden && _bar.focus) {
 			const auto shift = st::lineWidth + st::historyUnreadBarMargin;
@@ -549,6 +556,15 @@ std::optional<int> ListWidget::scrollTopForPosition(
 			return height() - (_visibleBottom - _visibleTop);
 		}
 		return std::nullopt;
+	} else if (!_items.empty()
+		&& (_aroundPosition == position
+			|| _initialAroundPosition == position)
+		&& messageUnknown) {
+		if (_refreshingViewer) {
+			return std::nullopt;
+		}
+		const auto available = _visibleBottom - _visibleTop;
+		return std::max((height() / 2) - available / 2, 0);
 	} else if (_items.empty()
 		|| isBelowPosition(position)
 		|| isAbovePosition(position)) {
@@ -871,6 +887,7 @@ void ListWidget::updateAroundPositionFromNearest(int nearestIndex) {
 	}
 	const auto newPosition = _items[_aroundIndex]->data()->position();
 	if (_aroundPosition != newPosition) {
+		_initialAroundPosition = _aroundPosition;
 		_aroundPosition = newPosition;
 		crl::on_main(this, [=] { refreshViewer(); });
 	}

Telegram/SourceFiles/history/view/history_view_list_widget.h

@@ -612,6 +612,7 @@ private:
 
 	Data::MessagePosition _aroundPosition;
 	Data::MessagePosition _shownAtPosition;
+	Data::MessagePosition _initialAroundPosition;
 	Context _context;
 	int _aroundIndex = -1;
 	int _idsLimit = kMinimalIdsLimit;

Telegram/SourceFiles/history/view/history_view_replies_section.cpp

@@ -133,19 +133,26 @@ rpl::producer<Ui::MessageBarContent> RootViewContent(
 } // namespace
 
 RepliesMemento::RepliesMemento(
-	not_null<HistoryItem*> commentsItem,
-	MsgId commentId)
-: RepliesMemento(commentsItem->history(), commentsItem->id, commentId) {
-	if (commentId) {
+	not_null<History*> history,
+	MsgId rootId,
+	MsgId highlightId)
+: _history(history)
+, _rootId(rootId)
+, _highlightId(highlightId) {
+	if (highlightId) {
 		_list.setAroundPosition({
-			.fullId = FullMsgId(
-				commentsItem->history()->peer->id,
-				commentId),
+			.fullId = FullMsgId(_history->peer->id, highlightId),
 			.date = TimeId(0),
 		});
 	}
 }
 
+RepliesMemento::RepliesMemento(
+	not_null<HistoryItem*> commentsItem,
+	MsgId commentId)
+: RepliesMemento(commentsItem->history(), commentsItem->id, commentId) {
+}
+
 void RepliesMemento::setFromTopic(not_null<Data::ForumTopic*> topic) {
 	_replies = topic->replies();
 	if (!_list.aroundPosition()) {

Telegram/SourceFiles/history/view/history_view_replies_section.h

@@ -365,11 +365,7 @@ public:
 	RepliesMemento(
 		not_null<History*> history,
 		MsgId rootId,
-		MsgId highlightId = 0)
-	: _history(history)
-	, _rootId(rootId)
-	, _highlightId(highlightId) {
-	}
+		MsgId highlightId = 0);
 	explicit RepliesMemento(
 		not_null<HistoryItem*> commentsItem,
 		MsgId commentId = 0);