This fixes a regression of PR #11266 that dropped the case where neither the option 'Ignore project unit system and use the default' is set nor an active document exists. In this case nothing happens even if the user changed the unit system.
This fixes a regression of PR #11266 that dropped the case where neither the option 'Ignore project unit system and use the default' is set nor an active document exists. In this case nothing happens even if the user changed the unit system.