From 08e1d3cd66cb09bd2c6a99a4a4aceb8ef71b8da0 Mon Sep 17 00:00:00 2001
From: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>
Date: Thu, 9 Jun 2022 04:01:37 +1000
Subject: [PATCH] Fix mind unvisit crash (#8682)

---
 Content.Server/Mind/Mind.cs | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/Content.Server/Mind/Mind.cs b/Content.Server/Mind/Mind.cs
index 61fb22b986..9f51860411 100644
--- a/Content.Server/Mind/Mind.cs
+++ b/Content.Server/Mind/Mind.cs
@@ -279,7 +279,7 @@ namespace Content.Server.Mind
 
             if (entity != null)
             {
-                if (!entMan.TryGetComponent<MindComponent>(entity.Value, out component))
+                if (!entMan.TryGetComponent(entity.Value, out component))
                 {
                     component = entMan.AddComponent<MindComponent>(entity.Value);
                 }
@@ -309,10 +309,18 @@ namespace Content.Server.Mind
             if(OwnedComponent != null)
                 mindSystem.InternalAssignMind(OwnedComponent.Owner, this, OwnedComponent);
 
-            if (VisitingEntity != null
-                && (ghostCheckOverride // to force mind transfer, for example from ControlMobVerb
-                    || !entMan.TryGetComponent(VisitingEntity!, out GhostComponent? ghostComponent) // visiting entity is not a Ghost
-                    || !ghostComponent.CanReturnToBody))  // it is a ghost, but cannot return to body anyway, so it's okay
+            // Don't do the full deletion cleanup if we're transferring to our visitingentity
+            if (alreadyAttached)
+            {
+                // Set VisitingEntity null first so the removal of VisitingMind doesn't get through Unvisit() and delete what we're visiting.
+                // Yes this control flow sucks.
+                VisitingEntity = null;
+                IoCManager.Resolve<IEntityManager>().RemoveComponent<VisitingMindComponent>(entity!.Value);
+            }
+            else if (VisitingEntity != null
+                  && (ghostCheckOverride // to force mind transfer, for example from ControlMobVerb
+                      || !entMan.TryGetComponent(VisitingEntity!, out GhostComponent? ghostComponent) // visiting entity is not a Ghost
+                      || !ghostComponent.CanReturnToBody))  // it is a ghost, but cannot return to body anyway, so it's okay
             {
                 RemoveVisitingEntity();
             }
@@ -402,11 +410,7 @@ namespace Content.Server.Mind
             DebugTools.AssertNotNull(oldVisitingEnt);
 
             var entities = IoCManager.Resolve<IEntityManager>();
-            if (entities.HasComponent<VisitingMindComponent>(oldVisitingEnt))
-            {
-                entities.RemoveComponent<VisitingMindComponent>(oldVisitingEnt);
-            }
-
+            entities.RemoveComponent<VisitingMindComponent>(oldVisitingEnt);
             entities.EventBus.RaiseLocalEvent(oldVisitingEnt, new MindUnvisitedMessage());
         }