Warnings before first setting save

Hi,

Before I save the first time the settings i get a lot of warnings. Also all the default values are only displaying the first char like “a” from “audio/mpeg”.

The warnings are:
Warning: Illegal string offset ‘main_poster’ in /homepages/htdocs/app/wp-content/plugins/podlove-web-player/settings.php on line 167

Warning: Cannot assign an empty string to a string offset in /homepages/htdocs/app/wp-content/plugins/podlove-web-player/settings.php on line 167

Warning: Illegal string offset ‘main_poster’ in /homepages/htdocs/app/wp-content/plugins/podlove-web-player/settings.php on line 169

Steps to reproduce:
* Install version 2.1.0 of this plugin
* Open the settings page

Regards,
Marvin