Describe the bug

Filler worked fine placing sandstone slabs. Suddenly my minecraft world crashed. Removing the QuarryPlus mod stopped the crashing. Also deleting the specific filler machine active using Amulet Editor fixed the crashes.

Edit: After doing some testing, this crash happens when choosing an area which already has slabs partly placed.

If you start this filler (filled with slabs of the same type!) it will crash when it reaches an already placed slab

If your server/client has crashed, please give me the crash report.

https://pastebin.com/wCb9f3c6

I'll take a look

Confirmed

Fixed in the latest release. Thank you for your report.