So it took me a bit to figure this out and ill will be posting this on their github issues as well as the topic i found that explained it also had this issue.

the quote from this topic 13rac1/Minecraft-Water-Erosion#10

This issue here is caused by your mod water-erosion and immersive-portals having the same refmap name main.refmap.json, whats happening is your refmap is getting overwritten by immersive-portals which is then obviously causing major issues.

The fix for this is to simply rename your refmap so that it contains your mod id. Example: erosion.refmap.json, this needs to be changed in your build.gradle and the refmap entry in erosion.mixins.json

At least thats my hope, as i removed your mod and things loaded.

EDIT: post i made on immersive portals github. qouteall/ImmersivePortalsModForForge#103

Thanks for reporting, but this should be in williambl/piston-control-forge.

My refmap is set to pistoncontrol.refmap.json, so there shouldn't be any conflicts there. Could you send the full log on gist, pastebin or similar, in a new issue on the forge repo? Thanks again for reporting this.

Alright, might want to change the forge page then, cause the issues option sent me here

Ah, thanks.