The client of a friend of me crashes as soon as a /give command is executed, seems to apply to both single player and multiplayer. In case of multiplayer we assume he's A, when B executes a /give command for B (/give B 46 64) it stills crashes client A. The exact same thing happens when /give was executed through a command block (this is how we found out in the first place). All other commands like /summon seem to work just fine. Attached is a crash output.