fix(server): remove misleading "Agent not available" warning.

Signed-off-by: Deluan <deluan@navidrome.org>

core/scrobbler/play_tracker_test.go

@@ -35,9 +35,12 @@ var _ = Describe("PlayTracker", func() {
 		ctx = request.WithPlayer(ctx, model.Player{ScrobbleEnabled: true})
 		ds = &tests.MockDataStore{}
 		fake = fakeScrobbler{Authorized: true}
-		Register("fake", func(ds model.DataStore) Scrobbler {
+		Register("fake", func(model.DataStore) Scrobbler {
 			return &fake
 		})
+		Register("disabled", func(model.DataStore) Scrobbler {
+			return nil
+		})
 		tracker = newPlayTracker(ds, events.GetBroker())
 
 		track = model.MediaFile{
@@ -61,6 +64,11 @@ var _ = Describe("PlayTracker", func() {
 		_ = ds.Album(ctx).(*tests.MockAlbumRepo).Put(&album)
 	})
 
+	It("does not register disabled scrobblers", func() {
+		Expect(tracker.(*playTracker).scrobblers).To(HaveKey("fake"))
+		Expect(tracker.(*playTracker).scrobblers).ToNot(HaveKey("disabled"))
+	})
+
 	Describe("NowPlaying", func() {
 		It("sends track to agent", func() {
 			err := tracker.NowPlaying(ctx, "player-1", "player-one", "123")