From a2983a5ee082532a8304d447da2c09142756bdf7 Mon Sep 17 00:00:00 2001
From: IProduceWidgets <107586145+IProduceWidgets@users.noreply.github.com>
Date: Mon, 6 Jan 2025 15:02:02 -0500
Subject: [PATCH] safe dictionary assignment (#5587)

---
 Robust.Server/GameObjects/EntitySystems/MapLoaderSystem.cs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Robust.Server/GameObjects/EntitySystems/MapLoaderSystem.cs b/Robust.Server/GameObjects/EntitySystems/MapLoaderSystem.cs
index 98644cb61..c956a9c97 100644
--- a/Robust.Server/GameObjects/EntitySystems/MapLoaderSystem.cs
+++ b/Robust.Server/GameObjects/EntitySystems/MapLoaderSystem.cs
@@ -1017,8 +1017,8 @@ public sealed class MapLoaderSystem : EntitySystem
                 // Skip removed tile definitions.
                 if (!_tileDefManager.TryGetDefinition(prototypeId, out var definition))
                     continue;
-
-                tileIdMap.Add(definition.TileId, origId);
+                if (!tileIdMap.ContainsKey(definition.TileId))
+                    tileIdMap.Add(definition.TileId, origId);
             }
 
             // Assign new IDs for all new tile types.