Bug on settings page

Hello,

Like you plugin a lot, thank you for great job done with it.

Just for your info: I bumped into issue with latest version of the plugin. When trying to update default text section on setting page I get notice (with debug mode on surely), that blocks the page refresh. It does not prevent completely from plugin usage, but it’s quite annoying.

Notice: Undefined index: mr_char_encoding in /home/f/foralien/tprosto.foralien.com/public_html/wp-content/plugins/multi-rating/includes/class-settings.php on line 702

Warning: Cannot modify header information – headers already sent by (output started at /home/f/foralien/tprosto.foralien.com/public_html/wp-content/plugins/multi-rating/includes/class-settings.php:702) in /home/f/foralien/tprosto.foralien.com/public_html/wp-includes/pluggable.php on line 1196

https://wordpress.org/plugins/multi-rating/