Crash with scoreboard / tp command

I make a little minigame, and i had command block with the title command. To test my minigame, i kill giants. After many freezes, the game crash. Here the crash report. I use also the clock in command block of Sethbling with fill stone and redstone_block.

Thanks

Edit : I think that i was mistaken, i think that is not the title command but the scoreboard command : the crash report has this error with the

/scoreboard players set @a MediumSword 1 {SelectedItemSlot:0,Inventory:[{Slot:0b,tag:{display:{Name:"Medium Sword"}}}]}
and the /scoreboard players operation BasicSword Experience -= @a[score_BasicSword_min=1] Dealt

Re Edit : I have recrashed and the command was a /scoreboard too :

/scoreboard players set @a BasicSword 0

Re re Edit : Another crash with the debug now

Description: Executing command block

java.lang.NullPointerException: Executing command block
	at java.util.Collections.addAll(Collections.java:3526)
	at ad.b(SourceFile:152)
	at z.a(SourceFile:47)
	at akw.a(SourceFile:92)
	at aos.b(SourceFile:60)
	at oq.a(SourceFile:482)
	at oq.c(SourceFile:193)
	at net.minecraft.server.MinecraftServer.w(SourceFile:570)
	at net.minecraft.server.MinecraftServer.v(SourceFile:506)
	at cln.v(SourceFile:132)
	at net.minecraft.server.MinecraftServer.run(SourceFile:422)
	at java.lang.Thread.run(Thread.java:695)