From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Tue, 21 Jun 2016 22:54:34 -0400
Subject: [PATCH] Fix Double World Add issues
Vanilla will double add Spider Jockeys to the world, so ignore already added.
Also add debug if something else tries to, and abort before world gets bad state
In 1.17 the entire entity state manager was rewritten. no longer applies, needs
further information on new state manager
similar check added by mojang
diff --git a/src/main/java/net/minecraft/server/level/ServerLevel.java b/src/main/java/net/minecraft/server/level/ServerLevel.java
index 0a613f94d1c796267636e1a343aeee65a49ffed5..335928d60dbfc07644ffeab366900c5e77e99d56 100644
--- a/src/main/java/net/minecraft/server/level/ServerLevel.java
+++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
@@ -1032,6 +1032,7 @@ public class ServerLevel extends net.minecraft.world.level.Level implements Worl
// CraftBukkit start
private boolean addEntity0(Entity entity, CreatureSpawnEvent.SpawnReason spawnReason) {
org.spigotmc.AsyncCatcher.catchOp("entity add"); // Spigot
+ if (entity.valid) { MinecraftServer.LOGGER.error("Attempted Double World add on " + entity, new Throwable()); return true; } // Paper
if (entity.removed) {
// WorldServer.LOGGER.warn("Tried to add entity {} but it was marked as removed already", EntityTypes.getName(entity.getEntityType())); // CraftBukkit
return false;
