'c' (a nil value) (Character) (?)

Localscript in tool

local tool = script.Parent
local plr = tool.Parent.Parent
local mouse = plr:GetMouse()
local Crystals = game.Workspace.Crystals
local c = plr.Character --here
local hum = c.Humanoid --here

local storage = game.ReplicatedStorage.CrystalStorage

local RegenTime = math.random(5,10)

local period = math.random(4,15)
game.Workspace.Area.Touched:connect(function(plr)
local function onActivate()
 if mouse.Target.Name == "Crystal" then
	mouse.Target.Owner.Value = c
		local a = hum:LoadAnimation(tool.Handle.Animation)
		a:Play()
		wait(period)
		a:Stop()
	for i,a in pairs(game.Workspace.Crystals:GetChildren()) do
			if a:IsA("UnionOperation") then
				if a.Owner.Value == c then
					a.Parent = storage
					wait(RegenTime)
					a.Parent = Crystals
					a.Owner.Value = nil
				end
			end
	end
	end
end


tool.Activated:connect(onActivate)
end)