Game crashes when cycling spells in spellbook

[AlexJ314]

https://github.com/Mithion/ArsMagica2/blob/6d6b68002363b2569c2f2300c8f9146ad800bbc6/src/main/java/am2/spell/SpellUtils.java#L487-L488 Looking at the crash log, it turns out that the variable "max" can hold the value of null, crashing Minecraft with a null pointer exception. To fix this crash simply, check to make sure the variable "max" isn't null before comparing to 0.

Edit: I'm playing 1.7.10