https://gist.github.com/thelegitdolt/05ed593ec78badb9630748dda64f068d i just got a crash from putting a banner pattern inside a loom, vanilla patterns seem to be fine

i will see if i can get the crash to stop by removing mods by myself later, currenlty am in school

It looks like the BannerRenderer can't get the Material for the corresponding BannerPattern. (See line 111 in BannerRenderer)
The BannerRenderer looks up the Material in a map, but since no Material exists for the BannerPattern, it gets a null Material, which causes the crash.
Register your banner patterns appropriately before the Sheets class gets loaded.
I'm pretty sure this is not a Blueprint issue, but I will reopen this issue if it is.

it's probably a mod incompat i'll do testing

Could be.
I don't think it's a Blueprint issue because Blueprint's BannerManager uses the BannerPattern#create() method provided by Forge.

i've also ran into this using the neapolitan one, so i don't think it's a problem with registry

it's probably a mod incompat i'll do testing

it's with pollen

Probably should report it to Pollen then.
As I said before, Blueprint's BannerManager uses the BannerPattern#create() method provided by Forge, meaning this issue would be an incompatibility at the individual mod level.

Neopolitan registers its banner patterns in the constructor of the Neapolitan class by classloading NeapolitanPaintingTypes.
This makes me think that Pollen is loading the Sheets class early.

actually i did a little more testing and it seems to be an enhanced mushrooms problem. I'll report it to them. Thanks for hearing me