From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 1 Jun 2016 23:29:17 -0400
Subject: [PATCH] Reset Ender Crystals on Dragon Spawn

Crystals can end up in a bad state in certain conditions which causes
an exception on the expected number of crystals going negative.

This ensures the crystals/pillars are in expected state when the dragon spawns.

See #3522

diff --git a/src/main/java/net/minecraft/world/level/dimension/end/EndDragonFight.java b/src/main/java/net/minecraft/world/level/dimension/end/EndDragonFight.java
index ec51369448a7f84ee65915ca97a0f22093126caa..2eb6e548889cd05c9bd6fe5947ea5bce3b43eaaa 100644
--- a/src/main/java/net/minecraft/world/level/dimension/end/EndDragonFight.java
+++ b/src/main/java/net/minecraft/world/level/dimension/end/EndDragonFight.java
@@ -409,6 +409,7 @@ public class EndDragonFight {
         enderDragon.moveTo(0.0D, 128.0D, 0.0D, this.level.random.nextFloat() * 360.0F, 0.0F);
         this.level.addFreshEntity(enderDragon);
         this.dragonUUID = enderDragon.getUUID();
+        this.resetSpikeCrystals(); // Paper
         return enderDragon;
     }