[rygel] tracker: Fix potential null access warnings

[Jens Georg <jensgeorg src gnome org>]

commit 39df2ddf8ef956244e0bf6657da1734ebf9eb608
Author: Jens Georg <mail jensge org>
Date:   Fri Feb 14 00:35:29 2020 +0100

    tracker: Fix potential null access warnings

 src/plugins/tracker/rygel-tracker-category-container.vala | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/plugins/tracker/rygel-tracker-category-container.vala 
b/src/plugins/tracker/rygel-tracker-category-container.vala
index 8be8be9c..351df188 100644
--- a/src/plugins/tracker/rygel-tracker-category-container.vala
+++ b/src/plugins/tracker/rygel-tracker-category-container.vala
@@ -67,9 +67,9 @@ public abstract class Rygel.Tracker.CategoryContainer : Rygel.SimpleContainer {
             }
 
             if (container is MetadataValues) {
-                (container as MetadataValues).fetch_metadata_values.begin ();
+                ((MetadataValues) container).fetch_metadata_values.begin ();
             } else if (container is SearchContainer) {
-                (container as SearchContainer).get_children_count.begin ();
+                ((SearchContainer) container).get_children_count.begin ();
             }
         }
     }