Function stops working after one line is completed?

This function works up until the line where I wrote "STOPS WORKING" can anybody show me what's wrong with this?

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local createPartEvent = ReplicatedStorage.FISHKINDEVENTS:WaitForChild("YellowFish")

local function onCreatePartFired(player)
    wait(2)
    local coinz = game.ReplicatedStorage.PEOPLE[""..player.Name..""].FISHING.Coins
    local xpz = game.ReplicatedStorage.PEOPLE[""..player.Name..""].FISHING.XP

if player:findFirstChild("leaderstats") then
wait(0.1)
player.leaderstats.Coins.Value = player.leaderstats.Coins.Value + coinz.Value
player.leaderstats.XP.Value = player.leaderstats.XP.Value + xpz.Value --STOPS WORKING HERE
player.leaderstats.Fish.Value = player.leaderstats.Fish.Value + 1
end
end

createPartEvent.OnServerEvent:Connect(onCreatePartFired)