Version 1.6.12
When using the Cinderhearth, leads to minecraft crashing

Put any item into the smelting slot of the Cinderhearth, leads to the game immediately crashing

Expected item to instead smelt into desired result.

Crash Report
If it is a crash bug add your crash log here
crash-2023-08-24_22.49.32-server.txt

Fixed in alpha-20