I know its not that dangerous, but how do the devs expect us to deal with the event ?

I had this event when I was excavating a basement chamber. The ward flashed and I heard scratching noises, when I finally cleared out the pesky things they had murdered all my * boars, and broke my bonfire.

I have all the windows and doorways either shut or have iron grating over, but they came in through the chimney to break the bonfire, and of course my boars are in a open top pen so yeah porks on the menu I guess.

The biggest nuisance is the broken bonfire for my place, I have a large central chimney to house a bonfire but its not just a case of place bonfire and its all good.
I have to dismantle the whole bottom section of the fireplace to rebuild the bonfire, and be damn careful I dont break all the supports, or the middle of the hall comes down, and the fireplace is quiet complicated having stone supports with a stone surround and iron grating between the pillars... took about 3 in game days to rebuild.
I would place a iron grate in the chimney to prevent this but, smoke cant pass the grates... basically if the smoke can get out, the bats can get in.

... and do I have to build a enclosed and roofed shelter for my pigs, or grate the whole pen just to keep 'em alive ?

I get the feeling the devs didn't think this event out fully, no big deal but I would appreciate someway to not get my bonfire and boars broken each time the game goes batty :P