Issue with 1.0.1

I recently upgraded from 0.2.0 to 1.0.1 and had to revert due to issues. When I go to save a post I am left with a blank screen in the admin due to php errors. The issue appears to be related to how you have introduced ob_flush() on line 16.

https://ww.wp.xz.cn/plugins/only-one-category/