Use queued connections for automatically loading new tracks from Auto…

…DJPorcessor

This ensures that the stack of slots connected to the original signal is fully processed.
Fixes https://bugs.launchpad.net/mixxx/+bug/1941743

src/library/autodj/autodjfeature.cpp

@@ -60,10 +60,15 @@ AutoDJFeature::AutoDJFeature(Library* pLibrary,
     qRegisterMetaType<AutoDJProcessor::AutoDJState>("AutoDJState");
     m_pAutoDJProcessor = new AutoDJProcessor(
             this, m_pConfig, pPlayerManager, pLibrary->trackCollections(), m_iAutoDJPlaylistId);
+
+    // Connect loadTrackToPlayer signal as a queued connection to make sure all callbacks of a
+    // previous load attempt have been called (lp1941743)
     connect(m_pAutoDJProcessor,
             &AutoDJProcessor::loadTrackToPlayer,
             this,
-            &LibraryFeature::loadTrackToPlayer);
+            &LibraryFeature::loadTrackToPlayer,
+            Qt::QueuedConnection);
+
     m_playlistDao.setAutoDJProcessor(m_pAutoDJProcessor);
 
     // Create the "Crates" tree-item under the root item.