Client Crash Report: https://paste.ee/p/Z2HZW

Fml Client Latest: https://www.dropbox.com/s/zc87mwe2d8fseq1/fml-client-latest-b1434-sticky-piston.log?dl=1

 

The dedicated server doesn't crash tho.

 

We're using a sticky piston to push a block to complete a circuit. When the piston retracts to break the circuit, the client crashes.

The fact that it is only when retracting and not ALL the time seems to tell me that you have something that is editing the tile entity renderer or related objects to set them to null, which we can't control.

I'd start by removing these mods:

WARNING: coremods are present:
  NowWithRendering (hopperducts-mc1.8-1.4.5.jar)
  LoadingPlugin (random-things-1.8-3.5.2.jar)
  BabyAnimalsCore (BabyAnimals-1.8-2.jar)
  CodeChickenCorePlugin ([0]CodeChickenCore-1.8-1.0.5.36-universal.jar)
  FMLPlugin (Inventory Tweaks 1.60-dev-14.jar)
  CoreMod (Aroma1997Core-1.8-1.0.3.4.b43.jar)
  LoadPlugin (AlexIILLib-1.8-1.3.42.jar)
  BCModPlugin (zz-backpacks 1.8 - 3.0.3 beta 4 (1).jar)
  CCLCorePlugin (CodeChickenLib-1.8-1.1.2.133-universal.jar)
  CCCDeobfPlugin (unknown)
  VeinMinerCorePlugin (veinminer-0.27.0.jar)
  ItemPatchingLoader (ItemPhysic Full 1.1.4 mc1.8.jar)
  NEICorePlugin (NotEnoughItems-1.8-1.0.5.104-universal.jar)
  GenderLoadingPlugin ([1.8]Gender-1.0.4.jar)
  TransformerLoader (open-computers-1.8-1.5.12.29.jar)
  NowWithRendering (redstone-paste-1.8-1.7.1.jar)
Contact their authors BEFORE contacting forge

I found the issue. It was Tabula by iChun. I have sent the report to him.

I found the issue. It was Tabula by iChun. I have sent the report to him.

Pretty sure Tabula is for mod makers/modelers, so you probably don't need it.