I don't know if 1.12.2 is still being developed, but I thought I would leave this here.

MC: 1.12.2
Forge: 14.23.5.2854
Crafting Station: 0.1.7b
Gregtech Community Edition: 1.9.0.481

Crash Report:
crash-2020-05-09_03.45.54-client.txt

Brief description: The Quantum Chest from GTCE is made to store large amounts of a single item. However, when a crafting station is placed next to the quantum chest that already has an item type, a conflicting item type can attempted to be placed in the quantum chest via the crafting station's UI. This crashes, with the log as above. Repeatable every time I have tested this.

Revising the above, the crash can occur any time you attempt to put items into a quantum chest that the crafting station has connected to, there is no need for the quantum chest to have items inside it already.