Error when exporting link field

[wouter-vs]

When creating an export of content with a link field an error is thrown.

mb_strlen() expects parameter 1 to be string, object given

`
/vagrant/craft/app/helpers/ArrayHelper.php(236)

224 // Private Methods
225 // =========================================================================
226
227 /**
228 * The array_filter() callback function for filterEmptyStringsFromArray().
229 *
230 * @param string $val
231 *
232 * @return bool
233 */
234 private static function _isNotAnEmptyString($val)
235 {
236 return (mb_strlen($val) != 0);
237 }
238 }`

The problem is that the link field contains objects like the Craft\ElementCriteriaModel object that are getting passed to the filterEmptyStringsFromArray method.
I think these should already be filtered out before passing it to the ArrayHelper class.