`Tanks` enemies shooting through walls if up against them

In the `Tanks` game, If the enemies move up against the walls and shoot, the bullet goes through the walls. I probably forgot to check if a bullet hits a wall when it spawns.

Start by locating the Tanks enemy shooting and bullet-spawn logic, then reproduce the issue with an enemy pressed against a wall. The fix is complete when bullets spawned in that position do not pass through the wall while normal shots still work.

Written by the indexing model from the issue text.