A detailed walkthrough of the error, its code path and all known details is as follows:
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-- Head --
Thread: Client thread
Stacktrace:
	at biomesoplenty.common.handler.LeavesModelEventHandler$ModelLeaves.<init>(LeavesModelEventHandler.java:61)
	at biomesoplenty.common.handler.LeavesModelEventHandler.onModelBake(LeavesModelEventHandler.java:52)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_166_LeavesModelEventHandler_onModelBake_ModelBakeEvent.invoke(.dynamic)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
	at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:179)
	at net.minecraftforge.client.ForgeHooksClient.onModelBake(ForgeHooksClient.java:384)
	at net.minecraft.client.renderer.block.model.ModelManager.func_110549_a(ModelManager.java:30)
	at net.minecraft.client.resources.SimpleReloadableResourceManager.func_110542_a(SimpleReloadableResourceManager.java:121)
	at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:512)

-- Initialization --
Details:
Stacktrace:
	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:377)
	at net.minecraft.client.main.Main.main(SourceFile:123)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:483)
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
	at net.minecraft.launchwrapper.Launch.main(Launch.java:28)