modID and mod are never initialized.

https://github.com/SlimeKnights/Mantle/blob/master/src/mantle/event/Migration.java#L26-L29

public Migration(ModContainer m)
{
    m.getModId();
}

should be

public Migration(ModContainer m)
{
    mod = m;
    modID = m.getModId();
}

As far as I can tell, a1dc18f didn't actually fix anything (it was just a band-aid over a NPE caused by mod never being initialized) and could probably be reverted.

I'll take a look tomorrow