Fixes server shutdown crash & client error log spam. (#67)

Content.Client/GameObjects/Components/Inventory/ClientInventoryComponent.cs

@@ -27,6 +27,13 @@ namespace Content.Client.GameObjects
         private string TemplateName = "HumanInventory"; //stored for serialization purposes
         public event EventHandler<BoundKeyChangedMessage> OnCharacterMenuKey;
 
+        public override void OnRemove()
+        {
+            base.OnRemove();
+
+            Window.Dispose();
+        }
+
         public override void ExposeData(EntitySerializer serializer)
         {
             base.ExposeData(serializer);

Content.Server/GameObjects/Components/GUI/InventoryComponent.cs

@@ -13,6 +13,7 @@ using SS14.Shared.IoC;
 using SS14.Server.Interfaces.Player;
 using SS14.Shared.GameObjects.Serialization;
 using SS14.Shared.ContentPack;
+using System.Linq;
 
 namespace Content.Server.GameObjects
 {
@@ -44,7 +45,8 @@ namespace Content.Server.GameObjects
 
         public override void OnRemove()
         {
-            foreach (var slot in SlotContainers.Keys)
+            var slots = SlotContainers.Keys.ToList();
+            foreach (var slot in slots)
             {
                 RemoveSlot(slot);
             }