From 7ef81f909fc04e261a7c04d4822d79dd7fce6e65 Mon Sep 17 00:00:00 2001
From: Pascal Deklerck <pascal.deklerck@gmail.com>
Date: Wed, 13 Jun 2018 21:57:59 +0200
Subject: [PATCH] Defensive code for the case when addon_hooks key does not
 exist

---
 mathjax/mathjax.php | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mathjax/mathjax.php b/mathjax/mathjax.php
index 6f4dd395..91a6a066 100644
--- a/mathjax/mathjax.php
+++ b/mathjax/mathjax.php
@@ -27,7 +27,12 @@ function mathjax_uninstall() {
     Addon::unregisterHook('template_vars', 'addon/mathjax/mathjax.php', 'mathjax_template_vars');
 }
 
-function mathjax_template_vars($a, &$arr) {
+function mathjax_template_vars($a, &$arr)
+{
+    if (!array_key_exists('addon_hooks',$arr['vars']))
+    {
+	$arr['vars']['addon_hooks'] = array();
+    }
     $arr['vars']['addon_hooks'][] = "mathjax";
 }