(certain )Summon command freezes minecraft

The error I encountered was while using

/summon Creeper ~ ~1 ~ {Attributes:[,{Name:generic.movementSpeed,Base:1.0},{Name:generic.attackDamage,Base:999}]}

In a command block, I powered it via a lever and then all mobs froze and I could place illegal blocks (IE a torch on a wall stayed after I removed the wall).

No crash report, once a moderator checks this please write in the comments how to force crash minecraft, then I'll either comment the crash or edit this post if I can..