I tried playing with the world and crash after some time with the crash report below

Crash Report

I suggest in the net.dries007.tfc.world.classic.worldgen.WorldGenOreVeins.getVeinsAtChunk, check for null entries and if entries did null return an empty List of Vein instead

Your suggestion doesn't actually fix the bug, which is that the weighted collection of veins shouldn't be null.

Can you please post your full log + the contents of config/tfc/ore_spawn_data.json

The issue has been fixed

Except it's not is it, because there's evidently still a crash case when the user wants to spawn no veins.