Using the latest version of spigot for 1.8.3, the getDefaultPopulators is being passed null for the world argument which it should not do. Instead it should pass the actual world.

This issue was not present in the first 1.8.3 spigot update, and must have been created recently.

Crash report and log:
http://hastebin.com/kemegijaqa.tex

Other people have also had the problem:

• http://pastebin.com/cYDdfijf
• http://hastebin.com/uwiledecif.rb