(Semi-Solved) Setting itemstack variable to itemstack return value of a procedure causes crashing.

I am honestly tired of this, I've searched everything and found nothing. Here are the procedures involved.

https://imgur.com/a/0tGWHXn

https://imgur.com/a/pK350tY

Basically, I have a block that extracts different gases based on biome, height, etc.

To avoid making 300 IFELSEs and becoming Yandere Simulator 2, I am using a plugin for arrays.

The problem is, in the procedure ExtractGas, we have this variable called "gas", which I am trying to set it's itemstack value to the return value of the procedure ReturnGas. When I try to do so, this error shows up in the console:

https://gist.github.com/baicu12096/13f7b8527076283d1969266e6ca1298f

 If anyone can tell me what is happening, and possibly how I can fix it, I would appreciate. If it involves the autogenerated code, I will send it in no time.