Fix build issues w/ clang

src/Cache.cpp

@@ -1993,8 +1993,6 @@ Cache::getTimelineMentionsForRoom(lmdb::txn &txn, const std::string &room_id)
 void
 Cache::saveTimelineMentions(const mtx::responses::Notifications &res)
 {
-        json notif = res;
-
         QMap<std::string, QList<mtx::responses::Notification>> notifsByRoom;
 
         // Sort into room-specific 'buckets'

src/ChatPage.cpp

@@ -526,7 +526,7 @@ ChatPage::ChatPage(QSharedPointer<UserSettings> userSettings, QWidget *parent)
         connect(this,
                 &ChatPage::highlightedNotifsRetrieved,
                 this,
-                [this](const mtx::responses::Notifications &notif) {
+                [](const mtx::responses::Notifications &notif) {
                         try {
                                 cache::client()->saveTimelineMentions(notif);
                         } catch (const lmdb::error &e) {