What happens:

When entering a world with both CraftTweaker, Quark and Quark Oddities the game crashes

What you expected to happen:

To not crash

Script used:

https://gist.github.com/Insane96/1c13a39c726527cc09880bdfba945902

crafttweaker.log file:

https://gist.github.com/Insane96/1c13a39c726527cc09880bdfba945902

Affected Versions (Do not use "latest"):

• Minecraft: 1.15.2
• Forge: 31.1.27
• Crafttweaker: 6.0.0.10
• Using a server: Nop

Your most recent log file where the issue was present:

https://gist.github.com/Insane96/ee8c0bd707db49f5103a9ca80cc31df6

Reported over to Quark's too VazkiiMods/Quark#2007

I don't see how this could be an issue with my code, the only way I'm involved is by converting my ingredient to a vanilla ingredient, which if there was a problem with, would have crashed much sooner.

current guess:
The tag may not exist, I don't know if insane vanilla is a mod or your modpack, if it is your modpack, are you sure you are creating an item tag? if so, what is the script?
if insane vanilla is a mod:
it is probably adding tags too late or something / the tag is empty

Yeah, forgot to add the tag. But still the game shouldn't crash.
Also why is Quark mentioned in the crash-log?

I'm not sure what to tell you, but it's vanilla's code that is crashing, there is nothing I can do about that, like the tag isn't just empty, it straight up doesn't exist.