In a multiplayer server.
I created a scoreboard entry of a fake player as a joke. The Player name was "SarasDeliberateDeaths". It was under a deathcount score and the value entered was 9000 but the important part was that the player name was too large. It then kicked all players and we couldn't log back in. We kept getting the same error message about the string being too long. (See attachment)

What I expected to happen was...:
See a new entry of the scoreboard entry. Or give me an error in chat because I typed in the command

What actually happened was...:
See Above

Steps to Reproduce:
1. Run a multiplayer server
2. Create an objective
3. Have an op'd player type in a scoreboard entry with a player name larger that 16 characters, eg scoreboard players set reallylongplayername Deaths 1