So, long story short. I am not that new to creating modpacks, yet I ain't the best. So I couldn't seem to fix the problem. If I may get your help it would be very good. Either way. I made a modpack with a bunch of custom crafts. Yet yesterday, when I added a custom craft using an item from a mod, it crashed my game multiple times with me being unable to start it.
All I did understand is that there is an unsupported operation exception but as I went through my code I couldn't find anything that would cause one.
PS. I tried contacting the mod owner, he did not respond. T