Thanks for playing, so glad you enjoyed it!
If the player is allowed to overlap too much with the walls or furniture, then when the player shoots, the bullets will instantiate inside the wall and disappear. When this problem reared its head, I decided to control it simply by making the player's collider higher than you (or I) intuitively think it should be. There are of course other ways to handle this problem, but it's all about tradeoffs. :)
If you're looking for the key to escape the room with the desks and the TV, make sure you search the corpses of your enemies. The gun is in the next level.