From b13d066062ce15d63f40c9034f415fc1f687e24c Mon Sep 17 00:00:00 2001
From: Simon Kornblith <simon@simonster.com>
Date: Sun, 8 Jul 2012 13:04:09 -0400
Subject: [PATCH] Fix "TypeError: invalid 'in' operand arg" error introduced by
 d02fe6d9ab87f6bb888c8f00ac433da414643222 (thanks @adam3smith)

---
 .../content/zotero/xpcom/translation/translate_firefox.js   | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/chrome/content/zotero/xpcom/translation/translate_firefox.js b/chrome/content/zotero/xpcom/translation/translate_firefox.js
index d43e158ab..d1154ef63 100644
--- a/chrome/content/zotero/xpcom/translation/translate_firefox.js
+++ b/chrome/content/zotero/xpcom/translation/translate_firefox.js
@@ -103,8 +103,10 @@ Zotero.Translate.SandboxManager.Fx5DOMWrapper = function(obj, parent) {
 			var args = new Array(nArgs);
 			for(var i=0; i<nArgs; i++) {
 				var arg = arguments[i];
-				args[i] = ((typeof arg === "object" || typeof arg === "function")
-						&& "__wrappedDOMObject" in arg ? arg.__wrappedDOMObject : arg);
+				args[i] = (((typeof arg === "object" && arg !== null)
+						|| typeof arg === "function")
+					&& "__wrappedDOMObject" in arg
+					? arg.__wrappedDOMObject : arg);
 			}
 			return Zotero.Translate.SandboxManager.Fx5DOMWrapper(obj.apply(parent ? parent : null, args));
 		}