[1.20.1] Custom Anvil Block "Index 0 out of bounds for length 0" thrown when GUI opened or changed

[Guest]

Hey all, I'm trying to make a custom anvil that does all anvil actions for free (for fun, and testing).

The anvil opens the screen in game. I can put items in the two slots and type anything in the text box with no cost.

The item in the output slot can't be taken, but has enchantments (yet the name in the box isn't applied to the item) from the other slots and text box. When I change anything while the anvil screen is open, I get a "index out of bounds" error in the console but no crash. The log hints at an Array somewhere along the line related to a slot being the issue...

But I can't figure out WHICH variable (or where it is) that the error is talking about. I'm trying to use vanilla-ish code with some "light modification". But I can't go further unless I know what I broke. If what I'm doing is impossibly difficult to accomplish, or requires some easy little fix, please help.

 

The registry for the menu looks like this:

public static final RegistryObject<MenuType<NetheriteAnvilMenu>> NETHERITE_ANVIL_MENU =
            MENU_TYPES.register("netherite_anvil_menu",()->IForgeMenuType.create(NetheriteAnvilMenu::new));

The registry for the menutype (in the setupClient method) looks like this in my main mod class:

MenuScreens.register(ThingamajigsMenuTypes.NETHERITE_ANVIL_MENU.get(), NetheriteAnvilScreen::new);

 

Error log snippet: https://pastebin.com/BnxcH5Ft

Vanilla-based code for Anvil Block: https://mega.nz/file/pGRC3TAR#dWqJnzN9akEcYKK4ZaTtkkHGNRvlRkl2yTVRmdjveXU

Vanilla-based code for Anvil screen: https://mega.nz/file/QOpwHZwQ#S6cZzGhFQPGq4r_VLJSm2skFSRI24P9vz7Lm29j4yvM

Vanilla-based code for Anvil Menu: https://mega.nz/file/gDAX3bIR#Je9kdiT_rsl_SUnZYgOrEPcy9bCV-ZVmcFTIJdnB7Jk

Thingamajigs mod Ref class snippet used by Custom Anvil: https://mega.nz/file/EXQ0hYxY#BUUnp0URKpC8cQzs6U-je68YsDSjt-CSGRk70_kJHXw

I can't paste vanilla code here (too long and still WIP to be unique from vanilla) so I've provided links to downloads separately that will be removed once the issue is solved.

Here is a screenshot of the screen in game: https://mega.nz/file/Jf4BQR4A#S1DEjhg9MC497o8tEfSQ80rQHky45lz7gZYnaHxI_UM

Hope this is enough info and such to help identify the issue.

Edited January 20 by CreativeMasterBonin
added more clarification

[vemerion]

It looks like you are not calling this.addDataSlot(this.cost); in the last of the NetheriteAnvilMenu constructors.