fix bar crashing on monitor add/remove

src/connection/dbus/mpris.cpp

@@ -10,7 +10,10 @@
 #include "giomm/dbusproxy.h"
 
 std::shared_ptr<MprisController> MprisController::getInstance() {
-    static std::shared_ptr<MprisController> instance = std::shared_ptr<MprisController>(new MprisController());
+    static std::shared_ptr<MprisController> instance;
+    if (!instance) {
+        instance = std::shared_ptr<MprisController>(new MprisController());
+    }
     return instance;
 }
 
@@ -18,7 +21,7 @@ std::shared_ptr<MprisController> MprisController::createForPlayer(const std::str
     return std::shared_ptr<MprisController>(new MprisController(bus_name));
 }
 
-MprisController::MprisController() {
+MprisController::MprisController() : m_player_bus_name() {
     connect_session_async(sigc::mem_fun(*this, &MprisController::on_bus_connected));
 }
 
@@ -63,6 +66,33 @@ void MprisController::on_bus_connected(const Glib::RefPtr<Gio::AsyncResult> &res
     try {
         connection = Gio::DBus::Connection::get_finish(result);
 
+        // Per-player instances only need to create their own player proxy,
+        // not monitor all players on the bus.
+        if (!m_player_bus_name.empty()) {
+            if (!m_proxy) {
+                try {
+                    m_proxy = Gio::DBus::Proxy::create_sync(
+                        connection,
+                        m_player_bus_name,
+                        "/org/mpris/MediaPlayer2",
+                        "org.mpris.MediaPlayer2.Player");
+
+                    if (m_proxy) {
+                        m_proxy->signal_properties_changed().connect(
+                            sigc::mem_fun(*this, &MprisController::on_properties_changed));
+                        signalNotification();
+                        emit_cached_playback_status();
+                        emit_cached_position();
+                        emit_cached_can_seek();
+                    }
+                } catch (const Glib::Error &ex) {
+                    spdlog::error("DBus Connection Error for player {}: {}", m_player_bus_name, ex.what());
+                }
+            }
+            return;
+        }
+
+        // Singleton instance: monitor all MPRIS players on the bus.
         if (!m_dbus_proxy) {
             m_dbus_proxy = Gio::DBus::Proxy::create_sync(
                 connection,