User trys to right click some leg armor when its not equipped, the leg armor then equips to the chestplate slot in the armor inventory. The user then crashes.

2013-02-02 16:13:01 [WARNING] Failed to handle packet for USERSNIP/IPSNIP:
java.lang.ArrayIndexOutOfBoundsException: 4
java.lang.ArrayIndexOutOfBoundsException: 4
at rx.f(SourceFile:396)
at rz.q(SourceFile:1309)
at tx.a(SourceFile:237)
at vv.a(SourceFile:103)
at jb.a(SourceFile:218)
at jf.a(SourceFile:363)
at fn.a(SourceFile:58)
at cg.b(SourceFile:349)
at jf.d(SourceFile:61)
at jg.b(SourceFile:39)
at ic.b(SourceFile:30)
at net.minecraft.server.MinecraftServer.r(SourceFile:478)
at hx.r(SourceFile:248)
at net.minecraft.server.MinecraftServer.q(SourceFile:395)
at net.minecraft.server.MinecraftServer.run(SourceFile:329)
at gn.run(SourceFile:565)