Crash exploit - All players will crash if someone is transformed into a Tamed Wolf

If a player is transformed into a Tamed Wolf, all players on the server will crash because of a NullPointerException. This could essentially brick a server if a command block repeatedly runs a transform command on all players. Additionally, all players will crash if a player who has been previously transformed into a Tamed Wolf joins the game.

To replicate, run the following command:
/transform into minecraft:wolf {Owner:any_player_name_here}