Internal error: The raster layer does not have a spatial reference.

[NathanMoebus]

Attempting to load a set of PNG raster files but seeing the following error from the LayerViewStateChanged event.

Internal error: The raster layer does not have a spatial reference.

I don't see any way to set the spatial reference on the RasterLayer as the property only has a getter.  Also, I have world files that are in the same directory as the png files.

        private async Task LoadMap()
        {
            // create map
            Map myMap = new Map(SpatialReference.Create(3857));
            
            myMap.Basemap = new Basemap(BasemapStyle.ArcGISOceansBase);
            MyMapView.Map = myMap;

            MyMapView.LayerViewStateChanged += MyMapView_LayerViewStateChanged;

            // Get the file name
            string filepath = GetFilesPath();
            var files = Directory.GetFiles(filepath, "*.png");

            foreach (var file in files)
            {
                // Load the raster file
                Raster myRasterFile = new Raster(file);

                // Create the layer
                RasterLayer myRasterLayer = new RasterLayer(myRasterFile);

                // Add the layer to the map
                myMap.OperationalLayers.Add(myRasterLayer);

                try
                {
                    // Wait for the layer to load
                    await myRasterLayer.LoadAsync();

                    // Set the viewpoint
                    await MyMapView.SetViewpointGeometryAsync(myRasterLayer.FullExtent);
                }
                catch (Exception e)
                {
                    MessageBox.Show(e.ToString(), "Error");
                }
            }
        }

Sample - World File Contents