Java 1.8.0_51 64bit
CPU: Intel 12 Core i7-8700k @ 3.70GHz
Crash, Minecart, Mob spawning
When using a spawner minecart with a spider as the spawn potential, it has a chance to spawn a spider jockey, when this happens the game will crash with the error:
"The game crashed whilst exception ticking world
Error: java.lang.IllegalStateException: Entity is already tracked!"
It only effects spawner minecarts not normal spawers
From testing it looks to only be spider jockeys causing it not any other jockeys
Summon the following spawner in:
If you summon a few in a give it a minute or 2 the game will crash, when your relog you will see a spider jockey has just been spawned in.