Fix not being able to get the title of the playing audio file, due to using an obsolete way to get it in the playback class

playback.cpp

@@ -468,16 +468,14 @@ PlaybackInstance::PlaybackInstance() {
 
 }
 std::optional<std::string> PlaybackInstance::get_current_file() {
-    current_file_mutex.lock();
+    if (process == nullptr) return {};
-    std::optional<std::string> output = current_file;
+    if (!process->process_running()) return {};
-    current_file_mutex.unlock();
+    return process->get_file_path();
-    return output;
 }
 std::optional<std::string> PlaybackInstance::get_current_title() {
-    current_file_mutex.lock();
+    if (process == nullptr) return {};
-    std::optional<std::string> output = current_title;
+    if (!process->process_running()) return {};
-    current_file_mutex.unlock();
+    return process->get_title();
-    return output;
 }
 PlaybackInstance::~PlaybackInstance() {
     Stop();