Building design error

Summary: When I was trying to delete excess slabs from my building, an error occured:

release-702 (x64)
…onehearth/components/building/building_component.lua:1030: assertion failed!
stack traceback:
radiant/modules/common.lua:245: in function 'report_traceback’
radiant/modules/common.lua:256: in function <radiant/modules/common.lua:250>
[C]: in function ‘assert’
…onehearth/components/building/building_component.lua:1030: in function ‘_on_child_finished’
…onehearth/components/building/building_component.lua:773: in function 'instance’
radiant/modules/events.lua:291: in function <radiant/modules/events.lua:285>
[C]: in function 'xpcall’
radiant/modules/common.lua:265: in function 'xpcall’
radiant/modules/events.lua:285: in function 'trigger’
radiant/modules/events.lua:370: in function '_fire_async_triggers’
radiant/modules/events.lua:445: in function '_update’
radiant/server.lua:61: in function <radiant/server.lua:58>

Version Number and Mods in use: Alpha 21, no mods

Hope you can get some help,

I get this popping up more times then I get corn baskets going into the stockpile.

I just close permanently, and keep on trucking. If it gets too crazy, I save, and close the game down, and reload.

@Niolop, even if you’re still playing A21, that’s not the latest version of A21. It should be r707, you seem to have r702.

I can’t assure you that the error will not happen after updating, though. Do you have a screenshot of the building / slabs you were working on?