Refactor AsyncVidImageDataBase declaration in

VidDataChannel

lib/data_channel/channel.dart

@@ -16,7 +16,7 @@ import 'progress_info.dart';
 
 abstract class VidDataChannel {
   @protected
-  late final AsyncVidImageDataBase? source;
+  AsyncVidImageDataBase? source;
 
   final String url;