The Elder Guardian's Magic, which prevents you from damaging the Sea Monument by giving Mining Fatigue, can sometimes cause the game to crash on it's own, but when it is used after you remove the Mining Fatigue effect from yourself, it's a definite crash.
RE-EDIT: I further tested it, Thorns seems irrelevant to the issue, and other text regarding it was erased. The command for removing Mining Fatigue may also be irrelevant in itself, other than as a method of getting the Elder Guardian to re-apply the status effect to the player.

What I expected to happen was...:
Mining fatigue would be removed/run its course harmlessly.

What actually happened was...:
The game crashes when the Elder Guardian tries to apply/re-apply it.

Steps to Reproduce:
1. Find and enter a Sea Monument with an Elder Guardian still in it.
2. Gain the effects of its Magic.
3. Use "/effect <username> minecraft:mining_fatigue 0 0" to remove Mining Fatigue.
4. Elder Guardian will try to replace it.
5. Screen turns white.
6. Game will crash.

The attached crash reports were created after multiple attempts for verifying the cause of the crash. The earlier of the two, at "17.03.46" has VBO enabled, and the later one, at "17.14.25" does not.