Not sure who's responsible for this. On one hand it's The Lab attempting to do something, on the other it's Factorissimo doing something else.

Anyways, yea trying to clear The Lab mods surface crashes the game, pointing to F2 as the culprit. I can only assume it's due to F2 not allowing other mods to delete factories. While that's understandable for most other mods it does cause an issue with The Lab as you can't pick up factories by hand, deconstruction blueprints, or by hitting the Clear button.

Hopefully this mod is still being maintained and can make some kind of exception or workaround for The Blueprint Designer Lab?

Error while running event
factorissimo-2-notnotmelon::script_raised_destroy (ID 80)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function 'index'
__factorissimo-2-notnotmelon/control.lua:196: in function 'update_power_connection'
factorissimo-2-notnotmelon/control.lua:260: in function 'power_pole_destroyed'
factorissimo-2-notnotmelon/control.lua:812: in function <factorissimo-2-notnotmelon/control.lua:805>
stack traceback:
[C]: in function 'raise_event'
BlueprintLab_design/scripts/common.lua:36: in function 'DestroyEntity'
BlueprintLab_design/scripts/logic.lua:158: in function 'ClearLab'
BlueprintLab_design/scripts/gui.lua:50: in function <BlueprintLab_design/scripts/gui.lua:44>

Thanks for the report. Will look into this when there's time.