When trying to clear my ignored friends requests, if I click the Xs too quickly, I get an error as shown here.

The error appears to be a:

{error: {message: "This delete failed somehow‚ what the heck?ǃ?", status_code: 500}}

Attempting to bulk-clear your ignored friend requests is quite difficult because of this. I assume this is an optimistic concurrency failure, but there's no indication of when the prior delete completes, so it's not possible to consistently pace yourself to the point where it can succeed without watching the network debug panel.