Assert that index is valid

src/models/messageeventmodel.cpp

@@ -462,6 +462,7 @@ static LinkPreviewer *emptyLinkPreview = new LinkPreviewer;
 
 QVariant MessageEventModel::data(const QModelIndex &idx, int role) const
 {
+    Q_ASSERT(checkIndex(idx, QAbstractItemModel::CheckIndexOption::IndexIsValid));
     const auto row = idx.row();
 
     if (!m_currentRoom || row < 0 || row >= int(m_currentRoom->pendingEvents().size()) + m_currentRoom->timelineSize()) {