This will prevent the world from being opened because the player will always be looking at the campfire upon joining the world, immediately re-triggering this issue.

java.lang.NullPointerException: Unexpected error at net.minecraft.util.math.BlockPos.func_177971_a(SourceFile:70) at com.gildedgames.aether.common.entities.tiles.multiblock.TileEntityMultiblockDummy.getLinkedController(TileEntityMultiblockDummy.java:95) at com.gildedgames.aether.common.entities.tiles.multiblock.TileEntityMultiblockDummy.getHoverText(TileEntityMultiblockDummy.java:127) at com.gildedgames.aether.common.blocks.multiblock.BlockMultiBase.getHoverText(BlockMultiBase.java:90) at com.gildedgames.aether.client.renderer.ClientRenderHandler.onRenderIngameOverlay(ClientRenderHandler.java:144) at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_56_ClientRenderHandler_onRenderIngameOverlay_Pre.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.GuiIngameForge.pre(GuiIngameForge.java:907) at net.minecraftforge.client.GuiIngameForge.renderCrosshairs(GuiIngameForge.java:217) at net.minecraftforge.client.GuiIngameForge.func_175180_a(GuiIngameForge.java:148) at net.minecraft.client.renderer.EntityRenderer.func_181560_a(EntityRenderer.java:1420) 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)