https://gist.github.com/p455w0rd/4673e1d895f54727d1eeea89568c05eb

Please look into a paste service like github gist or pastebin rather than flooding issue trackers..at any rate, the issue is here: https://github.com/Insane-96/VulcaniteMod/blob/master/common/net/insane96mcp/vulcanite/events/LivingHurt.java#L80 ..they are assuming the player will be server side..they could annotate with @SideOnly(Side.SERVER) or just do an instanceof check..please contact this mod dev and report back if the author resolves the situation

this was fixed on their end