Building error/bug

Hi there, as soon as I start building a bit more complicated, or otherwise custom buildings, at some point an error will appear. It’s mostly a random error. Sometimes the UI stops working, or I can’t save, or walls dissapear and whatnot.

I will provide the text I received last:

release-702 (x64)
…onehearth/components/building/building_component.lua:1158: attempt to index local ‘fab’ (a nil value)
stack traceback:
radiant/modules/common.lua:245: in function 'report_traceback’
radiant/modules/common.lua:256: in function <radiant/modules/common.lua:250>
…onehearth/components/building/building_component.lua:1158: in function ‘can_scaffolding_clear’
…hearth/components/scaffolding/scaffolding_region.lua:379: 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’
…earth/components/fabricator/fabricator_component.lua:254: in function 'fn’
radiant/modules/events.lua:288: in function <radiant/modules/events.lua:285>
[C]: in function ‘xpcall’

radiant/controllers/time_tracker_controller.lua:84: in function 'set_now’
radiant/controllers/time_tracker_controller.lua:124: in function 'increment_now’
radiant/modules/timer.lua:13: 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:398: in function '_trigger_gameloop’
radiant/modules/events.lua:446: in function '_update’
radiant/server.lua:61: in function <radiant/server.lua:58>

.
The bug does not appear in pre-set buildings, such as a Dining hall or a tiny house.

Version of the game is Alpha 21