From 85e1b77caeb352b5088269be6938c4772976965f Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <odigiman@gmail.com>
Date: Tue, 5 Mar 2019 04:14:28 -0500
Subject: [PATCH] fix crash in getHighestBlockAt()

---
 src/pocketmine/level/format/SubChunk.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/pocketmine/level/format/SubChunk.php b/src/pocketmine/level/format/SubChunk.php
index 857277fe8..4a4aa4f43 100644
--- a/src/pocketmine/level/format/SubChunk.php
+++ b/src/pocketmine/level/format/SubChunk.php
@@ -138,6 +138,9 @@ class SubChunk implements SubChunkInterface{
 	}
 
 	public function getHighestBlockAt(int $x, int $z) : int{
+		if(empty($this->blockLayers)){
+			return -1;
+		}
 		for($y = 15; $y >= 0; --$y){
 			if(($this->blockLayers[0]->get($x, $y, $z) >> 4) !== BlockIds::AIR){
 				return $y;