(using bukkit to run a 1.13 server) 

Tried summoning killer bunny with /summon rabbit ~ ~ ~ {RabbitType:99}

instead summoned this, it has no health, cant be attacked, doesn't move, floats when blocks are broken below them, can be shoved around by player.

have tried to get rid of it by restarting server and going really far hoping it despawns

haven't figured out a way to get rid of it.