Move InternalChild assignment into BDL

osu.Game/Graphics/Containers/ExpandingContainer.cs

@@ -1,6 +1,7 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
@@ -40,18 +41,24 @@ namespace osu.Game.Graphics.Containers
             RelativeSizeAxes = Axes.Y;
             Width = contractedWidth;
 
-            InternalChild = CreateScrollContainer().With(s =>
-            {
-                s.RelativeSizeAxes = Axes.Both;
-                s.ScrollbarVisible = false;
-            }).WithChild(FillFlow = new FillFlowContainer
+            FillFlow = new FillFlowContainer
             {
                 Origin = Anchor.CentreLeft,
                 Anchor = Anchor.CentreLeft,
                 RelativeSizeAxes = Axes.X,
                 AutoSizeAxes = Axes.Y,
                 Direction = FillDirection.Vertical,
-            });
+            };
+        }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            InternalChild = CreateScrollContainer().With(s =>
+            {
+                s.RelativeSizeAxes = Axes.Both;
+                s.ScrollbarVisible = false;
+            }).WithChild(FillFlow);
         }
 
         protected virtual OsuScrollContainer CreateScrollContainer() => new OsuScrollContainer();