From 4adaa6f1fdbc95a31ae5b64ab77bedfdcfae9348 Mon Sep 17 00:00:00 2001
From: paweldomas <pawel.domas@jitsi.org>
Date: Tue, 4 Aug 2020 08:16:00 -0500
Subject: [PATCH] fix(last-n-limits): crash on undefined

---
 react/features/base/lastn/functions.js      | 4 ++++
 react/features/base/lastn/functions.test.js | 5 ++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/react/features/base/lastn/functions.js b/react/features/base/lastn/functions.js
index 338fa3ae7..23cfede81 100644
--- a/react/features/base/lastn/functions.js
+++ b/react/features/base/lastn/functions.js
@@ -40,6 +40,10 @@ export function validateLastNLimits(lastNLimits) {
  * of participants or {@code undefined} otherwise.
  */
 export function limitLastN(participantsCount, lastNLimits) {
+    if (!lastNLimits || !lastNLimits.keys) {
+        return undefined;
+    }
+
     let selectedLimit;
 
     for (const participantsN of lastNLimits.keys()) {
diff --git a/react/features/base/lastn/functions.test.js b/react/features/base/lastn/functions.test.js
index 3eb4d08d2..91b918b31 100644
--- a/react/features/base/lastn/functions.test.js
+++ b/react/features/base/lastn/functions.test.js
@@ -1,6 +1,9 @@
 import { limitLastN, validateLastNLimits } from './functions';
 
-describe('limitsLastN', () => {
+describe('limitLastN', () => {
+    it('handles undefined mapping', () => {
+        expect(limitLastN(0, undefined)).toBe(undefined);
+    });
     describe('when a correct limit mapping is given', () => {
         const limits = new Map();