From 7959097fe35c952e372b9a3c17d186942f741fdb Mon Sep 17 00:00:00 2001
From: James Seibel <jeseibel@gondtc.com>
Date: Fri, 24 Nov 2023 09:46:45 -0600
Subject: [PATCH] Fix a potential concurrent error on DhClientServerWorld
 shutdown

---
 .../distanthorizons/core/world/DhClientServerWorld.java    | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/core/src/main/java/com/seibel/distanthorizons/core/world/DhClientServerWorld.java b/core/src/main/java/com/seibel/distanthorizons/core/world/DhClientServerWorld.java
index 935299539..6d64be5ca 100644
--- a/core/src/main/java/com/seibel/distanthorizons/core/world/DhClientServerWorld.java
+++ b/core/src/main/java/com/seibel/distanthorizons/core/world/DhClientServerWorld.java
@@ -160,7 +160,12 @@ public class DhClientServerWorld extends AbstractDhWorld implements IDhClientWor
 		this.saveAndFlush();
 		this.f3Message.close();
 		
-		for (DhClientServerLevel level : this.dhLevels)
+		
+		// clear dhLevels to prevent concurrent modification errors
+		HashSet<DhClientServerLevel> levelsToClose = new HashSet<>(this.dhLevels);
+		this.dhLevels.clear();
+		// close each level
+		for (DhClientServerLevel level : levelsToClose)
 		{
 			LOGGER.info("Unloading level " + level.getServerLevelWrapper().getDimensionType().getDimensionName());