Fix a crash when sitting around with no room open

This doesn't check if m_room is null before accessing it's connection.
You can easily reproduce this by sitting around leaving NeoChat open
without entering a room.

src/models/messagecontentmodel.cpp

@@ -578,22 +578,21 @@ MessageComponent MessageContentModel::linkPreviewComponent(const QUrl &link)
     }
     if (linkPreviewer->loaded()) {
         return MessageComponent{MessageComponentType::LinkPreview, QString(), {{"link"_ls, link}}};
-    } else {
-        connect(linkPreviewer, &LinkPreviewer::loadedChanged, [this, link]() {
-            const auto linkPreviewer = dynamic_cast<NeoChatConnection *>(m_room->connection())->previewerForLink(link);
-            if (linkPreviewer != nullptr && linkPreviewer->loaded()) {
-                for (auto &component : m_components) {
-                    if (component.attributes["link"_ls].toUrl() == link) {
-                        // HACK: Because DelegateChooser can't switch the delegate on dataChanged it has to think there is a new delegate.
-                        beginResetModel();
-                        component.type = MessageComponentType::LinkPreview;
-                        endResetModel();
-                    }
+    }
+    connect(linkPreviewer, &LinkPreviewer::loadedChanged, this, [this, link]() {
+        const auto linkPreviewer = dynamic_cast<NeoChatConnection *>(m_room->connection())->previewerForLink(link);
+        if (linkPreviewer != nullptr && linkPreviewer->loaded()) {
+            for (auto &component : m_components) {
+                if (component.attributes["link"_ls].toUrl() == link) {
+                    // HACK: Because DelegateChooser can't switch the delegate on dataChanged it has to think there is a new delegate.
+                    beginResetModel();
+                    component.type = MessageComponentType::LinkPreview;
+                    endResetModel();
                 }
             }
-        });
-        return MessageComponent{MessageComponentType::LinkPreviewLoad, QString(), {{"link"_ls, link}}};
-    }
+        }
+    });
+    return MessageComponent{MessageComponentType::LinkPreviewLoad, QString(), {{"link"_ls, link}}};
 }
 
 QList<MessageComponent> MessageContentModel::addLinkPreviews(QList<MessageComponent> inputComponents)

src/models/messageeventmodel.cpp

@@ -84,21 +84,19 @@ void MessageEventModel::setRoom(NeoChatRoom *room)
         return;
     }
 
-    if (m_currentRoom) {
-        // HACK: Reset the model to a null room first to make sure QML dismantles
-        // last room's objects before the room is actually changed
-        beginResetModel();
-        m_currentRoom->disconnect(this);
-        m_currentRoom = nullptr;
-        endResetModel();
+    // HACK: Reset the model to a null room first to make sure QML dismantles
+    // last room's objects before the room is actually changed
+    beginResetModel();
+    m_currentRoom->disconnect(this);
+    m_currentRoom = nullptr;
+    endResetModel();
 
-        // Don't clear the member objects until the model has been fully reset and all
-        // refs cleared.
-        m_memberObjects.clear();
-        m_contentModels.clear();
-        m_reactionModels.clear();
-        m_readMarkerModels.clear();
-    }
+    // Don't clear the member objects until the model has been fully reset and all
+    // refs cleared.
+    m_memberObjects.clear();
+    m_contentModels.clear();
+    m_reactionModels.clear();
+    m_readMarkerModels.clear();
 
     beginResetModel();
     m_currentRoom = room;