From c408c7d057b3162f05cdefe60973286f34c4b6b0 Mon Sep 17 00:00:00 2001
From: nossr50 <nossr50@gmail.com>
Date: Thu, 31 Dec 2020 16:26:37 -0800
Subject: [PATCH] avoid concurrent exceptions on TransientEntityTracker

---
 .../com/gmail/nossr50/util/TransientEntityTracker.java   | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/main/java/com/gmail/nossr50/util/TransientEntityTracker.java b/src/main/java/com/gmail/nossr50/util/TransientEntityTracker.java
index 486842f7f..4b22abaea 100644
--- a/src/main/java/com/gmail/nossr50/util/TransientEntityTracker.java
+++ b/src/main/java/com/gmail/nossr50/util/TransientEntityTracker.java
@@ -6,6 +6,7 @@ import com.gmail.nossr50.skills.taming.TrackedTamingEntity;
 import com.gmail.nossr50.util.player.NotificationManager;
 import com.gmail.nossr50.util.skills.ParticleEffectUtils;
 import com.gmail.nossr50.util.text.StringUtils;
+import com.google.common.collect.ImmutableSet;
 import org.bukkit.Bukkit;
 import org.bukkit.Chunk;
 import org.bukkit.Location;
@@ -215,13 +216,17 @@ public class TransientEntityTracker {
         for(CallOfTheWildType callOfTheWildType : CallOfTheWildType.values()) {
             HashSet<TrackedTamingEntity> trackedEntities = getTrackedEntities(playerUUID, callOfTheWildType);
 
-            if(trackedEntities == null)
+            if(trackedEntities == null) {
                 continue;
+            }
 
-            for(TrackedTamingEntity trackedTamingEntity : trackedEntities) {
+            ImmutableSet<TrackedTamingEntity> immutableSet = ImmutableSet.copyOf(trackedEntities);
+
+            for(TrackedTamingEntity trackedTamingEntity : immutableSet) {
                 //Remove from existence
                 removeSummon(trackedTamingEntity.getLivingEntity(), player, false);
             }
+
         }
     }
 }