Slight fix

Author: half-potato

train.py

@@ -155,7 +155,7 @@ def training(dataset, opt, pipe, testing_iterations, saving_iterations, checkpoi
         render_pkg = renderFunc(viewpoint_cam, gaussians, pipe, bg, random=not opt.center_pixel)
         image, viewspace_point_tensor, visibility_filter, radii = render_pkg["render"], render_pkg["viewspace_points"], render_pkg["visibility_filter"], render_pkg["radii"]
 
-        if viewpoint_cam.alpha_mask is not None:
+        if hasattr(viewpoint_cam, "alpha_mask") and viewpoint_cam.alpha_mask is not None:
             alpha_mask = viewpoint_cam.alpha_mask.cuda()
             image *= alpha_mask
         # Loss