Stuck in Generating World screen

I exited my game in the nether, and the bar gets stuck on 99.9%. You would think when they stopped this form happening with the end they'd do it with the nether to in 1.12.1, BUT NO. NOW I HAVE TO WAIT EVEN LONGER FOR THE BUG TO BE FIXED. And double check it can't happen in the over world or in any other situation when you're at it.