From 9684949a1d8a82c642fc9c285ad8989d1ed32585 Mon Sep 17 00:00:00 2001
From: Edward Shen <code@eddie.sh>
Date: Thu, 8 Aug 2019 12:58:21 -0400
Subject: [PATCH] Add null handling for negative null. Closes #22.

---
 MMM-pages.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/MMM-pages.js b/MMM-pages.js
index 13b3aef..a5b7dc0 100644
--- a/MMM-pages.js
+++ b/MMM-pages.js
@@ -41,7 +41,7 @@ Module.register('MMM-pages', {
    */
   start: function() {
     this.curPage = 0;
-    
+
     // Compatibility
     if (this.config.excludes.length) {
       Log.warn(`[Pages]: The config option "excludes" is deprecated. Please use "fixed" instead.`);
@@ -79,7 +79,9 @@ Module.register('MMM-pages', {
         break;
       case 'PAGE_DECREMENT':
         Log.log('[Pages]: received a notification to decrement pages!');
-        this.changePageBy(-payload, -1);
+        // We can't just pass in -payload for situations where payload is null
+        // JS will coerce -payload to -0.
+        this.changePageBy(payload ? -payload : payload, -1);
         this.updatePages();
         break;
       case 'DOM_OBJECTS_CREATED':