This simple bookmarklet allows you to show the Better Errors page for the current rails app your are using. It is especially usefull for AJAX requests, for which the error page doesn't popup automatically.
Check out the amazing better_errors gem to get a better error page on your Ruby on Rails app, with a beautifull stack trace, live console, link to edit any file in your editor of choice and many more features !
Copy the content of the compiled file "better_errors_bookmarklet.js" in the URL part of your bookmark.
Tested in Firefox 18, Chrome 24 and Safari 6.1.