Reference map 'eureka-fabric-refmap.json' for vs_eureka.mixins.json could not be read. If this is a development environment you can ignore this message

If it doesn't cause an issue no problem. If it does make a new issue and upload the complete log and not just some random part

I am very used to this error breaking everything as it means mixins for the file it mentions won't work, but shockingly your mod works fine with it.
I saw it and instantly assumed it was responsible for horrible crashes, sorry.