ServerScriptService.StandHandler:82: attempt to index nil with 'WaitForChild?'

So, I'm trying to make a Jojo game and this is the stand handler in sss for my combat system. I got this error from the output when I tried to use the attack in testing mode. Here is what it said:

ServerScriptService.StandHandler:82: attempt to index nil with 'WaitForChild'

Here is the whole stand handler script (not a local script, a regular one.) the error line is number 82 :D

local TweenService = game:GetService("TweenService")
local RunService = game:GetService("RunService")

local mainFolder = game.ReplicatedStorage.StandFolder
local Summon = mainFolder.RemoteEvents.Summon
local Punching = mainFolder.RemoteEvents.Punching

Summon.OnServerEvent:Connect(function(player, isActive)
  local char = player.Character
  local hrp = char.HumanoidRootPart

  if isActive == true then
    local Stand = mainFolder.Models.Stand:Clone()
    local mainPart = Stand.PrimaryPart

    Stand.Parent = char
    mainPart.CFrame = hrp.CFrame

    local weld = Instance.new("ManualWeld")
    weld.Name = "Weld"
    weld.Part0 = mainPart
    weld.Part1 = hrp
    weld.C0 = mainPart.CFrame:ToObjectSpace(hrp.CFrame)
    weld.Parent = weld.Part0

    for i, bodyPart in pairs(Stand:GetChildren()) do
      if bodyPart:IsA("BasePart") and bodyPart ~= mainPart then
        local info = TweenInfo.new(0.45)
        local goal = {Transparency = 0}

        local tween = TweenService:Create(bodyPart, info, goal)
        tween:Play()
      end
    end

    local info = TweenInfo.new(0.5)
    local goal = {}
    goal.C0 = weld.Part0.CFrame:ToObjectSpace(weld.Part1.CFrame)
    goal.C1 = weld.Part0.CFrame:ToObjectSpace(weld.Part1.CFrame * CFrame.new(-3, 1.5, 3))

    local tween = TweenService:Create(weld, info, goal)
    tween:Play()

    local AnimControl = Stand.AnimationController
    local Idle = AnimControl:LoadAnimation(script.Animations.Idle)
    Idle:Play()
  else
    local Stand = char:FindFirstChild("Stand")
    local mainPart = Stand.PrimaryPart

    if Stand then
      if Stand.PrimaryPart:FindFirstChild("Weld") then
        local weld = Stand.PrimaryPart:FindFirstChild("Weld")

        for i, bodyPart in pairs(Stand:GetChildren()) do
          if bodyPart:IsA("BasePart") and bodyPart ~= mainPart then
            local info = TweenInfo.new(0.45)
            local goal = {Transparency = 1}

            local tween = TweenService:Create(bodyPart, info, goal)
            tween:Play()
          end
        end

        local info = TweenInfo.new(0.5)
        local goal = {}
        goal.C0 = weld.Part0.CFrame:ToObjectSpace(weld.Part1.CFrame)
        goal.C1 = weld.Part0.CFrame:ToObjectSpace(weld.Part1.CFrame)

        local tween = TweenService:Create(weld, info, goal)
        tween:Play()

        tween.Completed:Connect(function()
          Stand:Destroy()
        end)
      end
    end
  end
end)

local char = ("Players").Character
local Stand = char:WaitForChild("Stand")

local LeanAnim = Stand.AnimationController:LoadAnimation(script:WaitForChild("Lean"))
LeanAnim:Play()

if Stand then
  RunService.Heartbeat:Connect(function()
    if ("hum").MoveDirection ~= Vector3.new(0,0,0) then
      LeanAnim:AdjustWeight(1.001)
    else
      LeanAnim:AdjustWeight(0)
    end
  end)
end


Punching.OnServerEvent:Connect(function(player, currentAttack)
  local char = player.Character
  local Stand = char:FindFirstChild("Stand")
  local weld = Stand.HumanoidRootPart:FindFirstChild("Weld")

  local combatModule = require(script.Combat)

  Stand.HumanoidRootPart.Massless = true

  if currentAttack == 1 then
    combatModule.Main(weld, TweenService, Stand, script.Animations.RightPunch, char, currentAttack)
  elseif currentAttack == 2 then
    combatModule.Main(weld, TweenService, Stand, script.Animations.LeftPunch, char, currentAttack)
  elseif currentAttack == 3 then
    combatModule.Main(weld, TweenService, Stand, script.Animations.Smash, char, currentAttack)
  end
end)

I really hope someone can help with this