SB mod gun error

starbound.log excerpt
==========
[02:28:58.699] [Error] Exception while invoking lua function 'update'. (LuaException) Error code 2, [string "/items/active/weapons/weapon.lua"]:264: [string "/items/active/weapons/ranged/gunfire.lua"]:152: attempt to perform arithmetic on a nil value
stack traceback:
    [string "/items/active/weapons/ranged/gunfire.lua"]:152: in method 'damagePerShot'
    [string "/items/active/weapons/ranged/gunfire.lua"]:108: in method 'fireProjectile'
    [string "/items/active/weapons/ranged/gunfire.lua"]:47: in function <[string "/items/active/weapons/ranged/gunfire.lua"]:44>
stack traceback:
    [C]: in ?
    [C]: in function '_ENV.error'
    [string "/items/active/weapons/weapon.lua"]:264: in method 'setAbilityState'
    [string "/items/active/weapons/weapon.lua"]:467: in method 'setState'
    [string "/items/active/weapons/ranged/gunfire.lua"]:37: in method 'update'
    [string "/items/active/weapons/weapon.lua"]:182: in method 'update'
    [string "/items/active/weapons/ranged/gun.lua"]:26: in function <[string "/items/active/weapons/ranged/gun.lua"]:25>

Gun file excerpt- relevant info
==========
"animation" : "/items/active/weapons/ranged/gun.animation",

  "animationParts" : {

    "butt" : "",

    "middle" : "Fireduke.png",

    "barrel" : "",

    "muzzleFlash" : "/items/active/weapons/ranged/muzzleflash.png"

  },

  "animationCustom" : {

    "particleEmitters" : {

      "muzzleFlash" : {

        "particles" : [

          { "particle" : "rocketbarrelpuff", "offset" : [0.0, -0.2] }

        ]

      }

    },

    "sounds" : {

      "fire" : [ "/sfx/gun/mech_gatling1.ogg" ]

    }

  },

  "baseOffset" : [1.0, 0.1],

  "muzzleOffset" : [2.5, -0.2],



  "scripts" : ["/items/active/weapons/ranged/gun.lua"],


  "elementalType" : "fire",



  "primaryAbility" : {

    "scripts" : ["/items/active/weapons/ranged/gunfire.lua"],

    "class" : "GunFire",


    "fireTime" : 0.1,

    "baseDps" : 900,

    "energyUsage" : 5,

    "inaccuracy" : 0.1,

    "projectileCount" : 1,

    "fireType" : "auto",



    "projectileType" : "standardbullet",

    "projectileParameters" : {

      "knockback" : 8,

      "statusEffects" : [ "burning" ]

    },



    "stances" : {

      "idle" : {

        "armRotation" : 0,

        "weaponRotation" : 0,

        "twoHanded" : true,



        "allowRotate" : true,

        "allowFlip" : true

      },

      "fire" : {

        "duration" : 0,

        "armRotation" : 5,

        "weaponRotation" : 5,

        "twoHanded" : true,



        "allowRotate" : false,

        "allowFlip" : true

      },

      "cooldown" : {

        "duration" : 0.1,

        "armRotation" : 5,

        "weaponRotation" : 5,

        "twoHanded" : true,



        "allowRotate" : false,

        "allowFlip" : true

      }

    }

  }