JavaScript error parser

error-parser.js

function errorParser(err) {
  if (err) {
    if (typeof err === 'function') {
      err = err();
    }

    if (typeof err === 'object') {
      if ('responseText' in err) {
        err = err.responseText;

        try {
          err = JSON.parse(err);  
        } catch (e) {
        } finally {
          return this.parseError(err);
        }
      } else if ('message' in err) {
        return err.message;
      } else if ('error' in err) {
        return this.parseError(err.error);
      }
    }

    if (typeof err !== 'string') {
      err = err.toString();
    }

    try {
      err = Ember.$(new DOMParser().parseFromString(err, 'text/xml')).find('parsererror > div').html();
    } catch (e) {}

    return err;
  } else {
    return 'Unknown error';
  }
}