Fatal error ajax.php

Hi,
I’m getting a Fatal Error on WP 3.8

Fatal error: Cannot use object of type WP_Error as array in /wp-content/plugins/ajax-post-filter/lib/ajax.php on line 194

Any known fixes for this?

I’m using the regular shortcode with my CPT defined and taxonomies defined.

http://ww.wp.xz.cn/plugins/ajax-post-filter/