From 1a22b371cdf6d2638cdefc3fb8ae55e603c908ed Mon Sep 17 00:00:00 2001
From: EnZaXD <60033407+FlorianMichael@users.noreply.github.com>
Date: Thu, 9 May 2024 21:56:14 +0200
Subject: [PATCH] Handle bad heightmaps in 1.17->1.16.4 (#743)

---
 .../protocol1_16_4to1_17/packets/BlockItemPackets1_17.java    | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_16_4to1_17/packets/BlockItemPackets1_17.java b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_16_4to1_17/packets/BlockItemPackets1_17.java
index 715e686a..6c5b866d 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_16_4to1_17/packets/BlockItemPackets1_17.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_16_4to1_17/packets/BlockItemPackets1_17.java
@@ -339,6 +339,10 @@ public final class BlockItemPackets1_17 extends BackwardsItemRewriter<Clientboun
 
             CompoundTag heightMaps = chunk.getHeightMap();
             for (Tag heightMapTag : heightMaps.values()) {
+                if (!(heightMapTag instanceof LongArrayTag)) {
+                    continue; // Client can handle bad data
+                }
+
                 LongArrayTag heightMap = (LongArrayTag) heightMapTag;
                 int[] heightMapData = new int[256];
                 int bitsPerEntry = MathUtil.ceilLog2((currentWorldSectionHeight << 4) + 1);