Hello, I'm going to try to make it as detailed as possible but the walkthrough is simple enough.
So, lets say you have a mod that adds enchantments, in this case, V-Tweaks.
Now, you use the oddities enchanting table tweak, and pop a few enchantments until you get the Imperishable or Lumbering enchantment and don't apply it to the tool, just leave it in the pool of enchantments. Exit the enchantment table without enchanting your tool.
Then, simply deactivate the enchantment in the config and restart the game.
Voila! You crashed your world.
I report this because maybe a mod may get an update that disables or removes the enchantment from it's mod, and that would cause issues (well, on this VERY specific scenario).
Here's the log:
https://paste.dimdev.org/kazaduxeza.mccrash

Also, it seems that it fixes by itself, because the table resets to a default state when you try to open the world again.