I'm using forge 1.12.2 version 14.23.5.2838 and the 1.12-1.3.1 version of Simple Dimensions. When I use the command and attempt to create a new dimension, the game always crashes. Here is my crash report: https://paste.dimdev.org/iketoqahef.mccrash

getting exact the same error. If i join the world after the crash it is crashing again.
https://pastebin.com/6zh98u6B

After looking at this there is a bug in SimpleDimensions. There WorldCustom implementation overrides the init() method, and does not fire the event necessary to attach world capabilities. Dynamic Surroundings makes use of world capabilities.