Make deleting a visited entity not cleaning it up in the mind.

Content.Server/GameObjects/Components/Mobs/VisitingMindComponent.cs

@@ -0,0 +1,20 @@
+using Content.Server.Mobs;
+using Robust.Shared.GameObjects;
+
+namespace Content.Server.GameObjects.Components.Mobs
+{
+    [RegisterComponent]
+    public sealed class VisitingMindComponent : Component
+    {
+        public override string Name => "VisitingMind";
+
+        public Mind Mind { get; set; }
+
+        public override void OnRemove()
+        {
+            base.OnRemove();
+
+            Mind?.UnVisit();
+        }
+    }
+}

Content.Server/Mobs/Mind.cs

@@ -231,6 +231,9 @@ namespace Content.Server.Mobs
         {
             Session?.AttachToEntity(entity);
             VisitingEntity = entity;
+
+            var comp = entity.AddComponent<VisitingMindComponent>();
+            comp.Mind = this;
         }
 
         public void UnVisit()
@@ -241,7 +244,14 @@ namespace Content.Server.Mobs
             }
 
             Session?.AttachToEntity(OwnedEntity);
+            var oldVisitingEnt = VisitingEntity;
+            // Null this before removing the component to avoid any infinite loops.
             VisitingEntity = null;
+
+            if (oldVisitingEnt.HasComponent<VisitingMindComponent>())
+            {
+                oldVisitingEnt.RemoveComponent<VisitingMindComponent>();
+            }
         }
     }
 }