Fixed previewImage

PixiEditor/Models/DataHolders/Document/Document.cs

@@ -160,6 +160,7 @@ namespace PixiEditor.Models.DataHolders
             if (layersToCenter.Count == 0)
             {
                 return;
+            }
 
             DoubleCoords? maybePoints = ClipLayersAndGetEdgePoints(layersToCenter);
             if (maybePoints == null)

PixiEditor/ViewModels/SubViewModels/Main/FileViewModel.cs

@@ -148,6 +148,7 @@ namespace PixiEditor.ViewModels.SubViewModels.Main
                 Owner.BitmapManager.ActiveDocument.AddNewLayer(
                     "Image",
                     Importer.ImportImage(dialog.FilePath, dialog.FileWidth, dialog.FileHeight));
+                Owner.BitmapManager.ActiveDocument.UpdatePreviewImage();
             }
         }