Using GregTech CE (gregtech-1.12.2-1.8.13.465) , and SGCraft (SGCraft-2.0.2), spams the game, and log with:

[17:18:29] [Chunk Batcher 19/ERROR]:
CCL has caught an exception whilst rendering a block
BlockPos: x:-138, y:58, z:585
Block Class: class gregtech.common.blocks.surfacerock.BlockSurfaceRockFlooded
Registry Name: gregtech:surface_rock_flooded_1
Metadata: 7
State: gregtech:surface_rock_flooded_1[level=0,material=graphite]
Tile at position
Tile Class: null
Tile Id: null
Tile NBT: null
You can turn off player messages in the CCL config file.

java.lang.NullPointerException: null
[17:18:29] [Chunk Batcher 19/INFO]: [CHAT] CCL Caught an exception rendering a block. See the log for info.
[17:18:30] [Chunk Batcher 20/ERROR]:
CCL has caught an exception whilst rendering a block
BlockPos: x:-148, y:60, z:604
Block Class: class gregtech.common.blocks.surfacerock.BlockSurfaceRockFlooded
Registry Name: gregtech:surface_rock_flooded_0
Metadata: 12
State: gregtech:surface_rock_flooded_0[level=0,material=nickel]
Tile at position
Tile Class: null
Tile Id: null
Tile NBT: null
You can turn off player messages in the CCL config file.

java.lang.NullPointerException: null
[17:18:31] [Chunk Batcher 7/ERROR]:
CCL has caught an exception whilst rendering a block
BlockPos: x:-163, y:55, z:381
Block Class: class gregtech.common.blocks.surfacerock.BlockSurfaceRockFlooded
Registry Name: gregtech:surface_rock_flooded_1
Metadata: 3
State: gregtech:surface_rock_flooded_1[level=0,material=tin]
Tile at position
Tile Class: null
Tile Id: null
Tile NBT: null
You can turn off player messages in the CCL config file.

java.lang.NullPointerException: null

Removing SGCraft fixes this problem. Using newest Forge for 1.12.2. Have attached logs, and also reported to GregTech CE github :)

latest.log

I've got to be honest, I looked at where Greg injected his override for the custom block renderer in SGCraft specifically BaseAORenderingManager and can't see why that would create the error your seeing. The call he makes is just reflecting back to the original renderBlock method of the calling class.