Fix gallery scan (#2594)

The incorrect error check means that images is always 0, which means scanImages is also always true, which causes the images inside the zip to be unnecessarily rescanned every time.

internal/manager/task_scan_gallery.go

@@ -25,7 +25,7 @@ func (t *ScanTask) scanGallery(ctx context.Context) {
 		var err error
 		g, err = r.Gallery().FindByPath(path)
 
-		if g != nil && err != nil {
+		if g != nil && err == nil {
 			images, err = r.Image().CountByGalleryID(g.ID)
 			if err != nil {
 				return fmt.Errorf("error getting images for zip gallery %s: %s", path, err.Error())