Bukkit/CraftBukkit — comment on commit 0cffd7f7b04f0e045d4184cfc259a81004b97b51
File: src/main/java/org/bukkit/craftbukkit/CraftArt.java line 36
By chrisyco:

It's just defensive programming. It should never ever reach that line, but if it does, it'll crash with a nice message.