Reproducable. This is in design mode before building occurs.
Make a square foundation 42 by 42. Make a 3 by 3 staircase. Enclose top of second floor. Put individual blocks by staircase gives this error.
release-453 (x64)
…hearth/services/server/build/build_undo_manager.luac:6: assertion failed!
stack traceback:
[C]: ?
[C]: in function ‘assert’
…hearth/services/server/build/build_undo_manager.luac:6: in function 'begin_transaction’
stonehearth/services/server/build/build_service.luac:300: in function 'do_command’
stonehearth/services/server/build/build_service.luac:50: in function <stonehearth/services/server/build/build_service.luac:49>