Account for graph actions being able to delete the entity in ChangeNode.

Fixes an exception that occurs if a node action deletes a construction.

Content.Server/Construction/ConstructionSystem.Graph.cs

@@ -140,6 +140,10 @@ namespace Content.Server.Construction
             if(performActions)
                 PerformActions(uid, userUid, node.Actions);
 
+            // An action might have deleted the entity... Account for this.
+            if (!Exists(uid))
+                return false;
+
             // ChangeEntity will handle the pathfinding update.
             if (node.Entity is {} newEntity && ChangeEntity(uid, userUid, newEntity, construction) != null)
                 return true;

Content.Server/Construction/ConstructionSystem.Interactions.cs

@@ -403,7 +403,7 @@ namespace Content.Server.Construction
             foreach (var action in actions)
             {
                 // If an action deletes the entity, we stop performing actions.
-                if (!EntityManager.EntityExists(uid))
+                if (!Exists(uid))
                     break;
 
                 action.PerformAction(uid, userUid, EntityManager);