See FabricMC/fabric#3098. Mine Cells uses toLowerCase() without specifying the locale for a block state property enum:

When MIDDLE is used as a property value in a Turkish-locale environment, it gets turned into mıddle. The game then crashes with an exception from MC's property validation code.

That's what I get for trying to save a few lines of code 😅 I'll fix that for the next release, will link the commit later today!

Should be fixed with this commit: b3b5b5d