From 6d6d88512a8146939a9161bb03e95e3e97840439 Mon Sep 17 00:00:00 2001
From: John Flatness <john@zerocrates.org>
Date: Thu, 28 Dec 2017 02:02:09 -0500
Subject: [PATCH] Skip counting currentNesting if null

This is an error starting in PHP 7.2
---
 library/HTMLPurifier/Injector.php | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/library/HTMLPurifier/Injector.php b/library/HTMLPurifier/Injector.php
index 5060eef9..116b470c 100644
--- a/library/HTMLPurifier/Injector.php
+++ b/library/HTMLPurifier/Injector.php
@@ -157,11 +157,13 @@ abstract class HTMLPurifier_Injector
             return false;
         }
         // check for exclusion
-        for ($i = count($this->currentNesting) - 2; $i >= 0; $i--) {
-            $node = $this->currentNesting[$i];
-            $def  = $this->htmlDefinition->info[$node->name];
-            if (isset($def->excludes[$name])) {
-                return false;
+        if (!empty($this->currentNesting)) {
+            for ($i = count($this->currentNesting) - 2; $i >= 0; $i--) {
+                $node = $this->currentNesting[$i];
+                $def  = $this->htmlDefinition->info[$node->name];
+                if (isset($def->excludes[$name])) {
+                    return false;
+                }
             }
         }
         return true;