BugFix: harvester-carryall remote death

The d2k harvester would suddenly explode if the approaching carryall was
destroyed. This is because there was no distinction between the unit being
carried and the unit being reserved. To test you'll probably have to tweak
the turret missile in weapons.yaml so you can forcefire on the carryall.

* added a bool to check if carryall is actually holding it's target
* fixed harvester being stuck in reserved mode

OpenRA.Mods.D2k/Traits/AutoCarryall.cs

@@ -33,6 +33,7 @@ namespace OpenRA.Mods.D2k.Traits
 
 		// The actor we are currently carrying.
 		[Sync] Actor carrying;
+		bool isCarrying;
 
 		// TODO: Use ActorPreviews so that this can support actors with multiple sprites
 		Animation anim;
@@ -138,8 +139,8 @@ namespace OpenRA.Mods.D2k.Traits
 		{
 			if (carrying != null)
 			{
-				carrying.Kill(e.Attacker);
-				carrying = null;
+				if (isCarrying && carrying.IsInWorld && !carrying.IsDead)
+					carrying.Kill(e.Attacker);
 			}
 
 			UnreserveCarryable();
@@ -148,6 +149,8 @@ namespace OpenRA.Mods.D2k.Traits
 		// Called when carryable is inside.
 		public void AttachCarryable(Actor carryable)
 		{
+			isCarrying = true;
+
 			// Create a new animation for our carryable unit
 			anim = new Animation(self.World, RenderSprites.GetImage(carryable.Info), RenderSprites.MakeFacingFunc(self));
 			anim.PlayRepeating("idle");
@@ -157,6 +160,7 @@ namespace OpenRA.Mods.D2k.Traits
 		// Called when released
 		public void CarryableReleased()
 		{
+			isCarrying = false;
 			anim = null;
 		}