Negative Gun Slots

What happens when you have, say, a ship with six available gun slots, and you buy/recieve an outfit that takes away, say, eight? Does Nova recognize that you have -2 gun slots, does it stop at zero, or does it show an error ("you can't buy this because it would result in negative free slots")?

Is there anything else you think I should be thinking about in relation to this?

Nova can only check for free slots as required by the gun/turret flags on the outfit you are purchasing. If the outfit is set to modify max guns/turrets or grant additional outfits which will affect gun/turret slots then it can't take those into account and you will be able to purchase the item even if it would result in you having negative slots.

Additionally, there is bug where multiple copies of one outfit which is set to modify max guns/turrets will not stack. The work around for this is to not use that modtype but instead have the outfit grant x copies of another outfit which is flagged as a gun/turret. Of course this only works properly for adding slots since as stated above it can't tell if you have enough free slots when removing.