Save options bug

Hy!
I have this erorr messanges, can you help me out?

Warning: Illegal string offset ‘loading’ in /home/neocsat/public_html/wp-content/plugins/infinite-scroll/includes/options.php on line 74

Fatal error: Cannot use string offset as an array in /home/neocsat/public_html/wp-content/plugins/infinite-scroll/includes/options.php on line 74
This you can find, if you go the stetings–>reading and when you chancge example the page number and press save option buttton.

https://ww.wp.xz.cn/plugins/infinite-scroll/