Fix: Empty stylesheet error.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "eruda",
-  "version": "0.0.3",
+  "version": "0.0.4",
   "description": "Console for mobile JavaScript",
   "main": "index.js",
   "scripts": {

src/Elements/CssStore.es6

@@ -46,6 +46,8 @@ export default class CssStore
 
         util.each(document.styleSheets, (styleSheet) =>
         {
+            if (!styleSheet.cssRules) return;
+
             util.each(styleSheet.cssRules, (cssRule) =>
             {
                 var matchesEl = false;