From b632cea6b7286f586fcc4c64b59c1b998a6e48a4 Mon Sep 17 00:00:00 2001
From: Cameron Fischer <fischer.cameron@gmail.com>
Date: Thu, 7 Jan 2021 13:19:50 -0500
Subject: [PATCH] Fixed issue where [lookup[]] could emit undefined (#5376)

---
 core/modules/filters/lookup.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/modules/filters/lookup.js b/core/modules/filters/lookup.js
index 49c8e205a..2174e8c47 100644
--- a/core/modules/filters/lookup.js
+++ b/core/modules/filters/lookup.js
@@ -22,7 +22,7 @@ Export our filter function
 exports.lookup = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {
-		results.push(options.wiki.getTiddlerText(operator.operand + title) || operator.suffix);
+		results.push(options.wiki.getTiddlerText(operator.operand + title) || operator.suffix || '');
 	});
 	return results;
 };