Recently i've been trying to make a sort of hardcore style modpack. Alloy Forgery is perfect for this because of its customization. Im trying to gate landmark alloys behind individual alloy forge tiers, just to make progression a little bit more interesting. To do this, I added 3 individual forge bricks with KubeJS, instead of using vanilla blocks.
The mod really doesnt like when I do this. It causes fabric to throw an error saying the crash was caused by whatever mod the configured alloy forge's base material happens to be from. KubeJS blocks throw: Could not execute entrypoint stage 'main' due to errors, provided by 'kubejs'! Just as a troubleshooting option I tried using polished tuff from Twigs, which threw: Could not execute entrypoint stage 'main' due to errors, provided by 'twigs'!', and so on. In the ~10 mods i've tested, they've all behaved the same way when their blocks are used as alloy forge materials.
Full crash report can be found here

json for custom forge, located in moddata/alloy_forgery/alloy_forges
{ "material": "kubejs:deepslate_forge_brick", "tier": 1, "speed_multiplier": 1, "fuel_capacity": 55000 }

and here's the kubejs:

onEvent('block.registry', event => {
    event.create('deepslate_forge_brick', block => {
        block.material('stone')
        block.hardness(5)
        block.displayName('Deepslate Forge Brick')
    })
})

Thank you for reporting. Should be fixed as of owo-lib 0.3.14