Merge pull request #10118 from peppy/fix-collection-delete-crash

Fix hard crash on deleting a collection with no collection selected

osu.Game/Screens/Select/FilterControl.cs

@@ -189,7 +189,15 @@ private void load(OsuColour colours, IBindable<RulesetInfo> parentRuleset, OsuCo
                 }
             };
 
-            collectionDropdown.Current.ValueChanged += _ => updateCriteria();
+            collectionDropdown.Current.ValueChanged += val =>
+            {
+                if (val.NewValue == null)
+                    // may be null briefly while menu is repopulated.
+                    return;
+
+                updateCriteria();
+            };
+
             searchTextBox.Current.ValueChanged += _ => updateCriteria();
 
             updateCriteria();