discourse/app/assets/javascripts/discourse/lib/ajax-error.js.es6

export function throwAjaxError(undoCallback) {
  return function(error) {
    if (error instanceof Error) {
      Ember.Logger.error(error.stack);
    }

    if (typeof error === "string") {
      Ember.Logger.error(error);
    }

    // If we provided an `undo` callback
    if (undoCallback) { undoCallback(error); }

    let parsedError;
    if (error.responseText) {
      try {
        const parsedJSON = $.parseJSON(error.responseText);
        if (parsedJSON.errors) {
          parsedError = parsedJSON.errors[0];
        } else if (parsedJSON.failed) {
          parsedError = parsedJSON.message;
        }
      } catch(ex) {
        // in case the JSON doesn't parse
        Ember.Logger.error(ex.stack);
      }
    }
    throw parsedError || I18n.t('generic_error');
  };
}