Fix ship cannon reward despawn

[theballaam96]

Describe the bug
If you spawn the ship cannon reward, then enter a submap, and back out into Galleon, the reward will be gone but the slam switch will be pressed down. Isn't remedied unless you back out of the level entirely or otherwise force an entire level state reset.

To Reproduce
Steps to reproduce the behavior:

1. Slam the switch to spawn the reward
2. Enter the seasick ship
3. Exit the seasick ship
4. Profit

Expected behavior
Reward is at the top of the lighthouse

Platform
All platforms

Additional context
Vanilla bug