From c7a357d84c62df5bdec9de475ae0c49a3bcb8b5b Mon Sep 17 00:00:00 2001
From: Joonas Rikkonen <poe.regalis@gmail.com>
Date: Sun, 13 Aug 2017 20:00:52 +0300
Subject: [PATCH] Fix for exceptions when a human is targeting a removed entity
 while debugdraw is enabled, accessing AITarget position properties after the
 target has been destroyed doesn't throw an exception (but does log an error
 in debug builds).

---
 .../Source/Characters/AI/HumanAIController.cs |  2 +-
 .../Source/Characters/AI/AITarget.cs          | 26 +++++++++++++++++--
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/Barotrauma/BarotraumaClient/Source/Characters/AI/HumanAIController.cs b/Barotrauma/BarotraumaClient/Source/Characters/AI/HumanAIController.cs
index 0cd62a1ad..07db87e3a 100644
--- a/Barotrauma/BarotraumaClient/Source/Characters/AI/HumanAIController.cs
+++ b/Barotrauma/BarotraumaClient/Source/Characters/AI/HumanAIController.cs
@@ -21,7 +21,7 @@ namespace Barotrauma
 
         public override void DebugDraw(Microsoft.Xna.Framework.Graphics.SpriteBatch spriteBatch)
         {
-            if (selectedAiTarget != null)
+            if (selectedAiTarget?.Entity != null)
             {
                 GUI.DrawLine(spriteBatch,
                     new Vector2(Character.DrawPosition.X, -Character.DrawPosition.Y),
diff --git a/Barotrauma/BarotraumaShared/Source/Characters/AI/AITarget.cs b/Barotrauma/BarotraumaShared/Source/Characters/AI/AITarget.cs
index 11c42b50d..12491c615 100644
--- a/Barotrauma/BarotraumaShared/Source/Characters/AI/AITarget.cs
+++ b/Barotrauma/BarotraumaShared/Source/Characters/AI/AITarget.cs
@@ -31,12 +31,34 @@ namespace Barotrauma
 
         public Vector2 WorldPosition
         {
-            get { return Entity.WorldPosition; }
+            get
+            {
+                if (Entity == null)
+                {
+#if DEBUG
+                    DebugConsole.ThrowError("Attempted to access a removed AITarget\n" + Environment.StackTrace);
+#endif
+                    return Vector2.Zero;
+                }
+
+                return Entity.WorldPosition;
+            }
         }
 
         public Vector2 SimPosition
         {
-            get { return Entity.SimPosition; }
+            get
+            {
+                if (Entity == null)
+                {
+#if DEBUG
+                    DebugConsole.ThrowError("Attempted to access a removed AITarget\n" + Environment.StackTrace);
+#endif
+                    return Vector2.Zero;
+                }
+
+                return Entity.SimPosition;
+            }
         }
 
         public AITarget(Entity e)