fix

dart_filament/lib/dart_filament.dart

@@ -1,5 +1,6 @@
 library filament_dart;
 
+export 'dart_filament/entities/filament_entity.dart';
 export 'dart_filament/abstract_filament_viewer.dart';
 export 'dart_filament/filament_viewer_impl.dart';
 export 'dart_filament/dart_filament.g.dart';

dart_filament/native/src/FilamentViewer.cpp

@@ -1017,6 +1017,7 @@ namespace flutter_filament
     else if (!_swapChain)
     {
       Log("No swapchain");
+      return;
     }
 
     // if (_frameCount == 60)