[1.12] issue wen entering a dimension

[a-wizard]

Version Information

Minecraft version: 1.12.2
Forge version: 1.12.2-forge-14.23.5.2854
Other mods (if applicable): vanilla dimention, and mod dimention

Steps to reproduce:

1. enter a portal in a normal world

Expected Behavior:
sending me to the other dimention

Actual Behavior:
crashing again and again

Link to crash log (if applicable - use a site such as hastebin:
crash-2021-01-16_03.54.27-server.txt

ps: wen a deactivate the mod it work, but it also generate a overworld that isn't on cubic chunck and go back to the overworld on cubic chunck, also i ddoesn't understant well thing so if in the end there was a button or something that fix everything i'm very sorry to have waiste your time ^^' anyway have a good day and thx

[Barteks2x]

First the customspawner mod is incompatible with cubic chunks, but the actual crash issue can be fixed by disabling optimized compatibility generator option in cubic chunks config.