If it helps, I think it is caused because I tried placing the block while hovering over grass (tall grass before 1.13).
I don't think this matters, but I was also on a server.
Also, it still placed the block when I re-joined the server, it just crashes my client.
java.lang.NullPointerException: Unexpected error
at com.clussmanproductions.trafficcontrol.blocks.BlockTrafficLight.getItemVersionOfBlock(BlockTrafficLight.java:90)
at com.clussmanproductions.trafficcontrol.blocks.BlockTrafficLight.getPickBlock(BlockTrafficLight.java:104)
at mcp.mobius.waila.overlay.RayTracing.getIdentifierItems(RayTracing.java:140)
at mcp.mobius.waila.overlay.RayTracing.getIdentifierStack(RayTracing.java:73)
at mcp.mobius.waila.overlay.RayTracing.getTargetStack(RayTracing.java:57)
at mcp.mobius.waila.overlay.DecoratorRenderer.onRenderWorldLast(DecoratorRenderer.java:27)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_54_DecoratorRenderer_onRenderWorldLast_RenderWorldLastEvent.invoke(.dynamic)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182)
at net.minecraftforge.client.ForgeHooksClient.dispatchRenderLast(ForgeHooksClient.java:196)
at net.minecraft.client.renderer.EntityRenderer.func_175068_a(EntityRenderer.java:1432)
at net.minecraft.client.renderer.EntityRenderer.func_78471_a(EntityRenderer.java:1259)
at net.minecraft.client.renderer.EntityRenderer.func_181560_a(EntityRenderer.java:1062)
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1119)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:398)
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:497)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)```
If it helps, I think it is caused because I tried placing the block while hovering over grass (tall grass before 1.13).
I don't think this matters, but I was also on a server.
Also, it still placed the block when I re-joined the server, it just crashes my client.