Warning: Illegal string offset 'code' in ... class_wdsi_admin_pages.php

Slide in does not work.

Detailed: Saving Generals Settings in Slide in does not work.
And i get this Warnings:

Warning: Illegal string offset 'code' in /www/htdocs/w010566f/wp-content/plugins/slide-in/lib/class_wdsi_admin_pages.php on line 184

Warning: Illegal string offset 'code' in /www/htdocs/w010566f/wp-content/plugins/slide-in/lib/class_wdsi_admin_pages.php on line 184

Warning: Cannot modify header information - headers already sent by (output started at /www/htdocs/w010566f/wp-content/plugins/slide-in/lib/class_wdsi_admin_pages.php:184) in /www/htdocs/w010566f/wp-includes/pluggable.php on line 876