From f7d375c76ce5b504d4d361f594ab4dd4fa96f5f9 Mon Sep 17 00:00:00 2001
From: dordsor21 <dordsor21@gmail.com>
Date: Fri, 3 Jul 2020 16:29:27 +0100
Subject: [PATCH] Lazy heightmap range fix

---
 .../com/sk89q/worldedit/math/convolution/HeightMap.java    | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/worldedit-core/src/main/java/com/sk89q/worldedit/math/convolution/HeightMap.java b/worldedit-core/src/main/java/com/sk89q/worldedit/math/convolution/HeightMap.java
index 432445223..ea4d57ff3 100644
--- a/worldedit-core/src/main/java/com/sk89q/worldedit/math/convolution/HeightMap.java
+++ b/worldedit-core/src/main/java/com/sk89q/worldedit/math/convolution/HeightMap.java
@@ -286,7 +286,12 @@ public class HeightMap {
                     if (existing.getBlockType().getMaterial().isMovementBlocker()) {
                         int y0 = newHeight - 1;
                         for (int setY = y0, getY = curHeight - 1; setY >= curHeight; setY--, getY--) {
-                            BlockState get = session.getBlock(xr, getY, zr);
+                            BlockState get;
+                            if (getY >= 0 && getY < 256) {
+                                get = session.getBlock(xr, getY, zr);
+                            } else {
+                                get = BlockTypes.AIR.getDefaultState();
+                            }
                             if (get != BlockTypes.AIR.getDefaultState()) tmpBlock = get;
                             session.setBlock(xr, setY, zr, tmpBlock);
                             ++blocksChanged;