From 8a8093028de2cf31fc90290207a76656950b9756 Mon Sep 17 00:00:00 2001
From: Simon Kornblith <simon@simonster.com>
Date: Fri, 9 Aug 2013 11:00:55 -0400
Subject: [PATCH] Check if callback exists before calling

---
 chrome/content/zotero/xpcom/zotero.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/chrome/content/zotero/xpcom/zotero.js b/chrome/content/zotero/xpcom/zotero.js
index 7dbe63ba8d..76471f6486 100644
--- a/chrome/content/zotero/xpcom/zotero.js
+++ b/chrome/content/zotero/xpcom/zotero.js
@@ -814,10 +814,10 @@ Components.utils.import("resource://gre/modules/Services.jsm");
 				Zotero.DB.closeDatabase().then(function() {				
 					// broadcast that DB lock has been released
 					Zotero.IPC.broadcast("lockReleased");
-					callback();
+					if(callback) callback();
 				});
 			} else {
-				callback();
+				if(callback) callback();
 			}
 		} catch(e) {
 			Zotero.debug(e);