fix: chrome extension error

Author: kunal-mandalia

how-to-make-chrome-extensions/bear/content.js

@@ -6,7 +6,8 @@
 // })
 
 const re = new RegExp('bear', 'gi')
-const matches = document.documentElement.innerHTML.match(re)
+const matches = document.documentElement.innerHTML.match(re) || []
+
 chrome.runtime.sendMessage({
   url: window.location.href,
   count: matches.length