Fix dynamic metadata in some cases

For some reason, this sometimes gets set to nil. Fix to refer to the
current track in that case.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Application/PlaybackController.m

@@ -656,6 +656,7 @@ NSDictionary *makeRGInfo(PlaylistEntry *pe) {
 
 - (void)audioPlayer:(AudioPlayer *)player pushInfo:(NSDictionary *)info toTrack:(id)userInfo {
 	PlaylistEntry *pe = (PlaylistEntry *)userInfo;
+	if (!pe) pe = [playlistController currentEntry];
 	[pe setMetadata:info];
 	[playlistView refreshCurrentTrack:self];
 	[self sendMetaData];