wait for plugin initialization before returning via FlutterFilamentPlugin.create

flutter_filament/lib/filament/flutter_filament_plugin.dart

@@ -48,13 +48,15 @@ class FlutterFilamentPlugin extends FilamentViewer {
         ? nullptr
         : Pointer<Void>.fromAddress(sharedContext);
 
-    return FlutterFilamentPlugin._(channel,
+    var plugin = FlutterFilamentPlugin._(channel,
         renderCallback: renderCallback,
         renderCallbackOwner: renderCallbackOwner,
         resourceLoader: resourceLoader,
         driver: driverPtr,
         sharedContext: sharedContextPtr,
         uberArchivePath: uberArchivePath);
+    await plugin.initialized;
+    return plugin;
   }
 
   Future<FlutterFilamentTexture?> createTexture(