From 40a6f4dee97e47b0dbbfd9ab601aa7f928b22131 Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <odigiman@gmail.com>
Date: Thu, 30 Mar 2017 19:41:10 +0100
Subject: [PATCH] Elevated level close check to exception level As an
 assertion, this will crash on save if the level is already closed due to the
 provider being null.

---
 src/pocketmine/level/Level.php | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/pocketmine/level/Level.php b/src/pocketmine/level/Level.php
index 7afb386b4..0ad2e7fbc 100644
--- a/src/pocketmine/level/Level.php
+++ b/src/pocketmine/level/Level.php
@@ -416,7 +416,9 @@ class Level implements ChunkManager, Metadatable{
 	}
 
 	public function close(){
-		assert(!$this->closed, "Tried to close a level which is already closed");
+		if($this->closed){
+			throw new \InvalidStateException("Tried to close a level which is already closed");
+		}
 
 		if($this->getAutoSave()){
 			$this->save();