From 348e434beea89a05f3db81121d3630d5f45cc7f9 Mon Sep 17 00:00:00 2001
From: John Berlin <n0tan3rd@gmail.com>
Date: Thu, 6 Sep 2018 19:30:43 -0400
Subject: [PATCH] Pass sheet to deferredSheetExtraction rather than rules in
 order to ensure that the CSS rule extraction from style tags is guarded with
 null check on the property containing the css rules (edge case). (#378)

---
 pywb/static/wombat.js | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/pywb/static/wombat.js b/pywb/static/wombat.js
index 3f565a8c..bba61e7d 100644
--- a/pywb/static/wombat.js
+++ b/pywb/static/wombat.js
@@ -1352,9 +1352,10 @@ var _WBWombat = function($wbwindow, wbinfo) {
                 }
             }
 
-            PWorker.prototype.deferredSheetExtraction = function(rules) {
+            PWorker.prototype.deferredSheetExtraction = function(sheet) {
+                var rules = sheet.cssRules || sheet.rules;
                 // if no rules this a no op
-                if (rules.length === 0) return;
+                if (!rules || rules.length === 0) return;
                 function extract() {
                     // loop through each rule of the stylesheet
                     var media = [];
@@ -1450,7 +1451,7 @@ var _WBWombat = function($wbwindow, wbinfo) {
             // check no op condition
             if (this.sheet == null) return;
             // defer extraction to be nice :)
-            WBPreserWorker.deferredSheetExtraction(this.sheet.cssRules);
+            WBPreserWorker.deferredSheetExtraction(this.sheet);
         };
     }
 
@@ -1758,7 +1759,7 @@ var _WBWombat = function($wbwindow, wbinfo) {
                     if (wbUsePresWorker && elem.sheet != null) {
                         // we have a stylesheet so lets be nice to UI thread
                         // and defer extraction
-                        WBPreserWorker.deferredSheetExtraction(elem.sheet.cssRules);
+                        WBPreserWorker.deferredSheetExtraction(elem.sheet);
                     }
                 }
                 break;
@@ -2195,7 +2196,7 @@ var _WBWombat = function($wbwindow, wbinfo) {
             orig_setter.call(this, res);
             if (wbUsePresWorker && this.tagName === 'STYLE' && this.sheet != null) {
                 // got preserve all the things
-                WBPreserWorker.deferredSheetExtraction(this.sheet.rules);
+                WBPreserWorker.deferredSheetExtraction(this.sheet);
             }
         };