[rygel] tracker3: Fix crtical in cleanup query

[Jens Georg <jensgeorg src gnome org>]

commit cc1832f9b30adf0f5d1a5d8654856794a7715459
Author: Jens Georg <mail jensge org>
Date:   Sun Jun 7 17:33:44 2020 +0200

    tracker3: Fix crtical in cleanup query

 src/plugins/tracker3/rygel-tracker-category-all-container.vala | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/src/plugins/tracker3/rygel-tracker-category-all-container.vala 
b/src/plugins/tracker3/rygel-tracker-category-all-container.vala
index 5a2695b8..eedb74ef 100644
--- a/src/plugins/tracker3/rygel-tracker-category-all-container.vala
+++ b/src/plugins/tracker3/rygel-tracker-category-all-container.vala
@@ -72,9 +72,13 @@ public class Rygel.Tracker.CategoryAllContainer : SearchContainer,
                       error.message);
         }
 
-        message("RUnnin cleanup query for %s", this.item_factory.category);
+        message("Running cleanup query for %s", this.item_factory.category);
         var cleanup_query = new CleanupQuery (this.item_factory.category);
-        cleanup_query.execute.begin (RootContainer.connection, () => { query.result.close (); } );
+        cleanup_query.execute.begin (RootContainer.connection, () => {
+            if (query.result != null) {
+                query.result.close ();
+            }
+        });
     }
 
     public async void add_item (MediaFileItem item, Cancellable? cancellable)