Placing a Galacticraft lightning panel under certain circumstance causes a client crash. Furthermore, the SSP savegame becomes permanently corrupted, reproducing the crash on client login. The stacktrace seems to be related to foamfix:

java.lang.IllegalArgumentException: Cannot get unlisted property appeng.block.UnlistedDirection@7c10b885 as it does not exist in ExtendedBlockState{block=galacticraftcore:panel_lighting, properties=[type]}
	at pl.asie.foamfix.common.FoamyExtendedBlockState.getValue(FoamyExtendedBlockState.java:136)
	at appeng.client.render.model.AutoRotatingModel.func_188616_a(AutoRotatingModel.java:155)
	at micdoodle8.mods.galacticraft.core.client.model.block.ModelPanelLightBase.func_188616_a(ModelPanelLightBase.java:45)
	at net.minecraftforge.client.model.pipeline.ForgeBlockModelRenderer.render_foamfix_old(ForgeBlockModelRenderer.java:99)
	at net.minecraftforge.client.model.pipeline.ForgeBlockModelRenderer.render(ForgeBlockModelRenderer.java:44)
	at net.minecraftforge.client.model.pipeline.ForgeBlockModelRenderer.func_187497_c(ForgeBlockModelRenderer.java:64)
	at net.minecraft.client.renderer.BlockModelRenderer.func_187493_a(BlockModelRenderer.java:47)
	at net.minecraft.client.renderer.BlockModelRenderer.func_178267_a(BlockModelRenderer.java:38)
	at net.minecraft.client.renderer.BlockRendererDispatcher.func_175018_a(BlockRendererDispatcher.java:80)
	at codechicken.lib.render.block.CCBlockRendererDispatcher.func_175018_a(CCBlockRendererDispatcher.java:64)
	at net.minecraft.client.renderer.chunk.RenderChunk.func_178581_b(RenderChunk.java:200)
	at net.minecraft.client.renderer.chunk.ChunkRenderWorker.func_178474_a(SourceFile:100)
	at net.minecraft.client.renderer.chunk.ChunkRenderWorker.run(SourceFile:43)
	at java.lang.Thread.run(Unknown Source)

Full crash report is here.

Client Setup: Modern Skyblock 3 v3.2.0.1(current stable), spawned via Curse Client, defaults, no optifine (Was in.. I removed it for debugging purposes and got the same crash on relog).

Runtime: JRE8_161b12 -XX:+UseG1GC -Xmx6G -Xms6G -Dsun.rmi.dgc.server.gcInterval=2147483646 -XX:+UnlockExperimentalVMOptions -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M

System: Generic win10x64 consumer desktop, stable channel updates, nothing interferencing, nothing of interest to add here.

Notes: Has to have to do with the individual position (Edge, Next to Exu polished stone, Tier3 Mekanism Compressor, AE2 cable and TE Item duct), because I cannot replicate it in a fresh save. Yet my current savegame is permanently damaged. Forge's option to remove erroring entities/tile-entitites did not work (happily taking ideas, rollback would lose me a day).

This doesn't happen without FoamFix, does it? Did you check? This code in FoamFix emulates vanilla/Forge behaviour very closely and is misblamed surprisingly often - only once (with BiblioCraft) out of dozens of reports has it actually been unreproducible without FoamFix.

happily taking ideas

This is most likely a Galacticraft bug. I recommend removing the affected block with MCEdit!

I tried to test without Foamfix, tbh the 6GB RAM I can affort to allocate wont even run the pack to main menu :-(

Meanwhle I succesfully deleted the block using MCEdit and can resume the savegame. I'll reference this to galacticrafts issue system. Sorry for the trouble.

Try to reproduce without FoamFix first anyway, as they'll probably tell you to do the same. Perhaps on a smaller pack? GC and AE2 interactions are implicated, most likely with some sort of camouflage - you might be able to get away with just the two mods.

I'll see what I can do, copy the instance and delete content until it's able to load up on 6g.