When using OTG and trying to assign a custom generator to the dimension it appears to be be assigning the wrong ChunkProviderServer.

This is using: justenoughdimensions-1.12.2-1.6.0-dev.20171208.003733.jar

Here is the JED Debug output from a normal world.

https://pastebin.com/aAzKNaqx

Here is what happens when you try to use OTG in a JED DIM (this won't work at all without using Sponge):
https://pastebin.com/Pa3DU8nN

This is the crash log from joining the world in the new DIM when OTG is set in server.properties:
https://pastebin.com/BGdxhuJm

Here the crashlog if you use default as the level-type= in server.properties:
https://pastebin.com/qHfJUKrw

Here is the server files you can replicate this issue with as it's a bit confusing to get it working atm.
http://www.mediafire.com/file/d88q58bs1vyffi1/JED_Crash.zip

To replicate with these files:

1. Join and OP yourself
2. Use /TPJ 100
3. Server crashes.

What is the current situation with this?

OTG in general seems to be very problematic when it comes to compatibility with other mods... and in this case there is also Sponge in the mix.