FatalSafe
An elegant way to save yourself from accidentally locking out when you're struck by Fatal Errors while editing a live WordPress theme or a plugin. FatalSafe will switch to any theme in the default twenty series (i.e twentyfifteen), or deactivate the problematic plugin and gives you a chance to fix your error by keeping your site live.
Just remember to activate FatalSafe before starting your dirty live theme or plugin edit task.
