a1ff8ff#diff-aba3371336d2d6af7ab993ec944fa638R43-R46

look at that lines above;
: calls and assign to INSTANCE; : when it's called INSTANCE is not yet assigned

fix is simple: change this to

	static {
		BlockEntityRendererRegistryImpl.setup((t, function) -> renderers.put(t, function.apply(INSTANCE)));
	}

so that the INSTANCE field is used when it has been properly initialized.

Related discussion in fabric discord: https://discordapp.com/channels/507304429255393322/566276937035546624/648786511952871424

Thanks for the analysis, this should be fixed now!