catchSomeDrupalAjaxAlerts.js

(function ($) {

  Drupal.behaviors.catchSomeDrupalAjaxAlerts = {

    attach: function(context, settings) {

      // Replace this simple core function with one that won't blurt empty messages.
      Drupal.displayAjaxError = function (message) {
        if (message && !Drupal.beforeUnloadCalled) {
          alert(message);
        }
      }

      // Intercept ajaxError to handle certain messages.
      // Passthru to the default Drupal.ajaxError if we don't want to intercepts.
      Drupal.ajaxErrorDefault = Drupal.ajaxError;
      Drupal.ajaxError = function (xmlhttp, uri, customMessage) {
        try {
          var message = xmlhttp.error.message;
        }
        catch (e) {}

        // Handle various known cases.
        if (uri.indexOf('file/ajax') !== -1 && message == 'Unexpected end of JSON input') {
          // DO SOMETHING ELSE HERE
          $('body').append('<div class="error">SOMETHING HAPPENED PLEASE CONTACT 911</div>');
          return false;
        }
        else {
          // Default to pass back to Drupal's handler.
          return Drupal.ajaxErrorDefault(xmlhttp, uri, customMessage);
        }
      }
    }
  };
}