Add replace init function

OpenRA.Game/Map/ActorReference.cs

@@ -125,6 +125,15 @@ namespace OpenRA
 			InitDict.Add(init);
 		}
 
+		public void Replace<T>(T init) where T : ActorInit, ISingleInstanceInit
+		{
+			var original = GetOrDefault<T>();
+			if (original != null)
+				Remove(original);
+
+			Add(init);
+		}
+
 		public void Remove(ActorInit o) { initDict.Value.Remove(o); }
 
 		public int RemoveAll<T>() where T : ActorInit

OpenRA.Mods.Common/Traits/World/EditorActorLayer.cs

@@ -144,8 +144,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (!Players.Players.TryGetValue(ownerInit.InternalName, out var owner))
 			{
 				owner = worldOwner;
-				reference.Remove(ownerInit);
-				reference.Add(new OwnerInit(worldOwner.Name));
+				reference.Replace(new OwnerInit(worldOwner.Name));
 			}
 
 			return owner;

OpenRA.Mods.Common/Traits/World/EditorActorPreview.cs

@@ -245,11 +245,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		public void ReplaceInit<T>(T init) where T : ActorInit, ISingleInstanceInit
 		{
-			var original = reference.GetOrDefault<T>();
-			if (original != null)
-				reference.Remove(original);
-
-			reference.Add(init);
+			reference.Replace(init);
 			GeneratePreviews();
 			UpdateRadarColor();
 		}

OpenRA.Mods.Common/Traits/World/SpawnMapActors.cs

@@ -38,10 +38,7 @@ namespace OpenRA.Mods.Common.Traits
 				// If an actor's doesn't have a valid owner transfer ownership to neutral
 				var ownerInit = actorReference.Get<OwnerInit>();
 				if (!world.Players.Any(p => p.InternalName == ownerInit.InternalName))
-				{
-					actorReference.Remove(ownerInit);
-					actorReference.Add(new OwnerInit(world.WorldActor.Owner));
-				}
+					actorReference.Replace(new OwnerInit(world.WorldActor.Owner));
 
 				actorReference.Add(new SkipMakeAnimsInit());
 				actorReference.Add(new SpawnedByMapInit());