Like some other people I am also getting a black screen on LineageOS 14.1 (Galaxy S4). Same thing also happens on build 790 but thats just a preview so I will ignore that. Can't use the "send error log" button as well because it doesn't pop up. I attached a small log for now but you can contact/message me if you need anything more. I can also test a new version if you want me to.   Log_2018-05-21_18-43-04.txt