Various comments already pointed to problems that could come with a rough error-logging implementation. Because he used AJAX for every error, it creates a (unnecessary) strain on the network/server when in production. Besides this, the usefulness of the data logged may vary heavily. Therefore I suggest you do not log everything, like chrisacky points out. What exactly to log is an interesting resulting question.

I do fancy the idea of logging problems client-side, because they result in users leaving your site but leaving you without a clue what happened.