I just started up Minecraft 1.5 and wanted to test out the new command block commands, but to my horror, the /scoreboard teams ... commands don't work at all! It just gives me a message consisting of an "unexpected error". Luckily, I ran it on a server and got the complete error which is:

java.lang.NullPointerException

at ard.a(SourceFile:190)
at gw.a(SourceFile:67)
at hr.g(SourceFile:329)
at hr.b(SourceFile:126)
at y.a(SourceFile:52)
at hz.am(SourceFile:288)
at hz.r(SourceFile:256)
at net.minecraft.server.MinecraftServerq(SourceFile:397)
at net.minecraft.server.MinecraftServer.run.(SourceFile:331)
at gp.run(SourceFile:573)

And that's that! I hope that someone could confirm this bug.