Fix logout current connection crash

Make sure that the neochat can handle switching connection when the current one is logged out. This is mostly about using QPointer to handle use after free issues due to room objects being deleted.

src/models/messageeventmodel.cpp

@@ -629,6 +629,10 @@ QVariant MessageEventModel::data(const QModelIndex &idx, int role) const
 
 int MessageEventModel::eventIdToRow(const QString &eventID) const
 {
+    if (m_currentRoom == nullptr) {
+        return -1;
+    }
+
     const auto it = m_currentRoom->findInTimeline(eventID);
     if (it == m_currentRoom->historyEdge()) {
         // qWarning() << "Trying to find inexistent event:" << eventID;