From 0fb620a8d3c730da1f10d1d5ab45482d783a3b2d Mon Sep 17 00:00:00 2001
From: smoogipoo <smoogipoo@smgi.me>
Date: Mon, 25 Dec 2017 16:41:18 +0900
Subject: [PATCH] Make HitObject.Samples non-nullable

---
 osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs | 5 +++--
 osu.Game/Rulesets/Objects/HitObject.cs                   | 8 +++++++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs b/osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs
index c397ea47ef..be161b9ad3 100644
--- a/osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs
+++ b/osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs
@@ -84,10 +84,11 @@ namespace osu.Game.Rulesets.Objects.Drawables
         [BackgroundDependencyLoader]
         private void load(AudioManager audio)
         {
-            if (HitObject.Samples != null)
+            if (Samples.Count > 0)
             {
                 if (HitObject.SampleControlPoint == null)
-                    throw new ArgumentNullException(nameof(HitObject.SampleControlPoint), $"{nameof(HitObject)} must always have an attached {nameof(HitObject.SampleControlPoint)}.");
+                    throw new ArgumentNullException(nameof(HitObject.SampleControlPoint), $"{nameof(HitObject)}s must always have an attached {nameof(HitObject.SampleControlPoint)}."
+                                                                                          + $" This is an indication that {nameof(HitObject.ApplyDefaults)} has not been invoked on {this}.");
 
                 foreach (SampleInfo s in HitObject.Samples)
                 {
diff --git a/osu.Game/Rulesets/Objects/HitObject.cs b/osu.Game/Rulesets/Objects/HitObject.cs
index 56f7a2e1a2..4f06f6afe1 100644
--- a/osu.Game/Rulesets/Objects/HitObject.cs
+++ b/osu.Game/Rulesets/Objects/HitObject.cs
@@ -25,6 +25,8 @@ namespace osu.Game.Rulesets.Objects
         /// </summary>
         public virtual double StartTime { get; set; }
 
+        private List<SampleInfo> samples;
+
         /// <summary>
         /// The samples to be played when this hit object is hit.
         /// <para>
@@ -32,7 +34,11 @@ namespace osu.Game.Rulesets.Objects
         /// and can be treated as the default samples for the hit object.
         /// </para>
         /// </summary>
-        public List<SampleInfo> Samples;
+        public List<SampleInfo> Samples
+        {
+            get => samples ?? (samples = new List<SampleInfo>());
+            set => samples = value;
+        }
 
         [JsonIgnore]
         public SampleControlPoint SampleControlPoint;