“Please use the search functionality before reporting an issue. Also take a look at the closed issues!”
I search and look this #4526 #4673
Issue description:
Copying using ChemicalWasher

Steps to reproduce:

https://github.com/aidancbrady/Mekanism/issues/4526
https://github.com/aidancbrady/Mekanism/issues/4673

1.Open chemical washer gui
2.Place stackable item in first slot in hotbar
3.Hold shift and click on this item

Version (make sure you are on the latest version before reporting):

Forge: 1.10.2-forge1.10.2-12.18.3.2511
Mekanism: 1.10.2-9.2.3 and 9.2.4
Other relevant version: MCMultiPart 1.4.0,only mekanism

Fix this in 1.10.2 Pls :)

we're only fixing crash bugs in 1.10, and even that has been lax of late

#5214