Light sources break when switching graphics modes or when changing block light

Light sources break when switching graphics modes or when changing block light.

How to reproduce:
1. Load a world
2. Place a light source (e.g. torch)
3. Set the time to night
4. Go to video settings and switch the graphics mode to vibrant visuals
5. Observe the torch no longer emitting a light source
6. Resume the game and observe the torch regaining a light source
7. Go back to video settings and change the block light quality setting
8. Observe the torch once again no longer emitting a light source and the game running at a low FPS
9. Resume the game and observe the torch once again regaining a light source
10. Go back to video settings again and switch the graphics mode to fancy
11. Observe the torch no longer emitting a light source once again
12. Resume the game and observe the torch regaining a light source once again